/sci/ - Science & Math » Thread #14362525

290KiB, 1651x2048, __yakumo_yukari_touhou_drawn_by_op_na_yarou__497b0d595d01241802a26f1541cc1afd.jpg

View Same Google iqdb SauceNAO

/sqt/ /qtddtot/ - stupid questions thread

Anonymous Mon 04 Apr 02:07:38 2022 No.14362525 View Reply Original Report

Quoted By: >>14362770 >>14362864 >>14363238 >>14363254 >>14365743 >>14368169 >>14370520 >>14374805 >>14376317

Previously >>14341111

>what is /sqt/ for?
Questions regarding math and science. Also homework.
>where do I go for advice?
>>>/sci/scg or >>>/adv/
>where do I go for other questions and requests?
>>>/wsr/ >>>/g/sqt >>>/diy/sqt etc.
>how do I post math symbols (Latex)?
rentry.org/sci-latex-v1
>a plain google search didn't return anything, is there anything else I should try before asking the question here?
scholar.google.com
>where can I look up if the question has already been asked here?
archived.moe/sci
archive.wakarimasen.moe/sci
boards.fireden.net/sci
>how do I optimize an image losslessly?
trimage.org
pnggauntlet.com

>where can I get:
>books?
libgen.rs
z-lib.org
stitz-zeager.com
openstax.org
>articles?
sci-hub.st
>book recs?
sites.google.com/site/scienceandmathguide
4chan-science.fandom.com/wiki//sci/_Wiki
math.ucr.edu/home/baez/physics/Administrivia/booklist.html
>charts?
imgur.com/a/pHfMGwE
imgur.com/a/ZZDVNk1
>tables, properties and material selection?
www.engineeringtoolbox.com
www.matweb.com

Tips for asking questions here:
>attach an image (animal images are ideal. Grab them from >>>/an/)
>avoid replying to yourself
>ask anonymously
>recheck the Latex before posting
>ignore shitpost replies
>avoid getting into arguments
>do not tell us where is it you came from
>do not mention how [other place] didn't answer your question so you're reposting it here
>if you need to ask for clarification fifteen times in a row, try to make the sequence easy to read through
>I'm not reading your handwriting
>I'm not flipping that sideways picture
>I'm not google translating your spanish
>don't ask to ask
>don't ask for a hint if you want a solution
>xyproblem.info

Anonymous

View Same Google iqdb SauceNAO __flandre_scarlet_touhou_drawn_b (...).png, 605KiB, 1087x1176

Anonymous Mon 04 Apr 2022 02:35:11 No.14362610 Report

Quoted By: >>14362929

Unanswered questions:

Maths questions:
>>14342299
>>14348552 [Sure.]
>>14348566
>>14353791
>>14356806
>>14361317

Physics questions:
>>14345523
>>14352599
>>14359853

Biology questions:
>>14343193
>>14351039
>>14353089

Chemistry questions:
>>14354168

Stupid questions:
>>14344053
>>14344188
>>14344344
>>14353672
>>14355518
>>14359749
>>14361384

Anonymous

Anonymous Mon 04 Apr 2022 03:52:01 No.14362770 Report

Quoted By:

>>14362525
what's the equation to find center of thrust/thrust vector?

Anonymous

View Same Google iqdb SauceNAO 0f4.jpg, 75KiB, 770x600

Anonymous Mon 04 Apr 2022 04:38:17 No.14362864 Report

Quoted By: >>14370449

>>14362525
Ah yes, just what I needed, let me get a biology review here instead of asking this in the open.

Let's say my father is a genius, but I'm not, if I pass the Y gene to my offspring combined with the mother's intelligence (granted if she's intelligent), would it result in offspring equal or better in intelligence than my father?

Anonymous

Anonymous Mon 04 Apr 2022 04:47:20 No.14362885 Report

Quoted By:

>>14361317
This makes no sense without some context. What is going on?

Anonymous

Anonymous Mon 04 Apr 2022 05:10:32 No.14362929 Report

Quoted By: >>14362973 >>14378440

>>14362610
I don't like this smug vampire telling me that my question is stupid.

Anonymous

View Same Google iqdb SauceNAO how steesatsu became gay.png, 34KiB, 1362x101

Anonymous Mon 04 Apr 2022 05:35:32 No.14362973 Report

Quoted By:

>>14362929
you're replying to a homosexual pedophile hoping to groom underage b&s, that is why the "post here if you're a young noob" thread is obsessively maintained by anime spammers

Anonymous

View Same Google iqdb SauceNAO i am retarded.png, 19KiB, 501x77

Anonymous Mon 04 Apr 2022 08:37:49 No.14363238 Report

Quoted By: >>14363250 >>14363286 >>14363295 >>14370481

>>14362525
pls help me

Anonymous

Anonymous Mon 04 Apr 2022 08:43:12 No.14363250 Report

Quoted By: >>14363263

>>14363238
what have you tried?

Anonymous

Anonymous Mon 04 Apr 2022 08:45:08 No.14363254 Report

Quoted By:

>>14362525
>got diagnosed with schizoid personality disorder unironically.
Am I ngmi? Is my future being posting deranged copypasta on 4chan?

Anonymous

Anonymous Mon 04 Apr 2022 08:49:24 No.14363263 Report

Quoted By: >>14365261

>>14363250
I tried using the vector plane equation but I got lost.

Anonymous

Anonymous Mon 04 Apr 2022 09:06:57 No.14363286 Report

Quoted By:

>>14363238
I would like to add: do not use calculus

Anonymous

Anonymous Mon 04 Apr 2022 09:14:19 No.14363295 Report

Quoted By: >>14363420 >>14365261

>>14363238
I found an answer: (18,8,5) and r=3, though I BS'd it.

Anonymous

Anonymous Mon 04 Apr 2022 09:25:29 No.14363304 Report

Quoted By:

>>14342299
Just make a change of variables and integrate

$\Xi = (1 - x/L)$ , thus $d\Xi = -dx/L$

Anonymous

Anonymous Mon 04 Apr 2022 10:52:54 No.14363420 Report

Quoted By:

>>14363295
An update: r=3 is wrong.

Anonymous

View Same Google iqdb SauceNAO Untitled.png, 68KiB, 981x752

Anonymous Mon 04 Apr 2022 11:40:57 No.14363477 Report

Quoted By: >>14363582 >>14363624 >>14363675

how do I solve this

Anonymous

Anonymous Mon 04 Apr 2022 12:42:30 No.14363582 Report

Quoted By:

>>14363477
I would've loved to choose (C) but (B) is correct. Read Rolle's Theorem

Anonymous

View Same Google iqdb SauceNAO __mystia_lorelei_touhou_drawn_by (...).jpg, 126KiB, 866x1000

Anonymous Mon 04 Apr 2022 13:13:49 No.14363624 Report

Quoted By: >>14363627

>>14363477
I'd mark A.
$g$ is continuous on $[a, b]$ , differentiable on $(a, b)$ and $(g(8) - g(10)) / 2 = 0$ trivially implies the existence of such a $c$ by the mean value theorem.
Sure, she didn't literally write the mean value theorem formula out, but that's trivial and she properly checked everything else.

Anonymous

Anonymous Mon 04 Apr 2022 13:14:50 No.14363627 Report

Quoted By:

>>14363624
* $g(10) - g(8)$

Anonymous

Anonymous Mon 04 Apr 2022 13:33:56 No.14363675 Report

Quoted By:

>>14363477
C

Anonymous

Anonymous Mon 04 Apr 2022 16:28:11 No.14364029 Report

Quoted By: >>14364076 >>14364095

I have to be doing something unbelievably stupid here. Let $(x_i)_1^n$ be iid normal variables with variance $\epsilon^2$ . Consider $g(\epsilon)=\sum_i^n x_i^2/(2\epsilon^2)$ . Then:

$<br />\parital_\epsilon \mathbb{E}g(\epsilon)= \partial_\epsilon \frac n 2 = 0<br />\\<br />\mathbb{E}\partial_\epsilon g(\epsilon) = -\frac n {\epsilon}<br />$

Shouldn't we be able to interchange expectation and differentiation in this case? What am I missing?

Anonymous

Anonymous Mon 04 Apr 2022 16:44:25 No.14364076 Report

Quoted By: >>14364095

>>14364029
forgot to mention that the x_i are zero-mean

Anonymous

Anonymous Mon 04 Apr 2022 16:52:53 No.14364095 Report

Quoted By:

>>14364076
>>14364029
Figured it out please ignore. For anyone who is curious and was trying to apply something like dominated convergence note that the situation is complicated by the fact that the random variables are functions of the parameter epsilon. Therefore typical arguments for these operations don't work.

Anonymous

View Same Google iqdb SauceNAO out.webm, 2MiB, 1920x720

Anonymous Mon 04 Apr 2022 21:50:13 No.14364832 Report

Quoted By:

I found the solution to my problem, it was rotation matrices to fix the unmatching rest pose and euler order
I wish someone had told me that the euler order was not the display order but the order in which the rotation applied
Fuck do i hate math

Anonymous

View Same Google iqdb SauceNAO 1648562569551.jpg, 81KiB, 1079x1063

Anonymous Mon 04 Apr 2022 22:53:22 No.14364971 Report

Quoted By: >>14365002

is there a way to integrate over all possible paths? like, given two points in space A and B, and some sort of scalar field, is there a way to integrate over every possible path from point A to point B? is it possible numerically?

Anonymous

Anonymous Mon 04 Apr 2022 23:08:19 No.14365002 Report

Quoted By: >>14365560

>>14364971
Do you mean path integrals?

Anonymous

View Same Google iqdb SauceNAO sum.png, 3KiB, 121x37

Anonymous Mon 04 Apr 2022 23:39:25 No.14365063 Report

Quoted By: >>14365124

How would you prove whether this converges or diverges? Integral test maybe?

Anonymous

Anonymous Tue 05 Apr 2022 00:03:36 No.14365124 Report

Quoted By: >>14365373

>>14365063
$\frac{1}{\sqrt{n^2-1}} \geq \frac{1}{n} \forall n > 1$
So the series diverges by comparison.

Anonymous

Anonymous Tue 05 Apr 2022 00:57:42 No.14365261 Report

Quoted By:

>>14363263
Don't.

>>14363295
Since the tangent planes are parallel, the radius is half the distance between them. And yeah, it's not 3.

To find the center, you know it lies in the intersection of the given planes. Calculate the equation of this line.

Then, for the same reason above, the center lies in the plane which is equidistant to the tangent planes, namely, x - 2y + z = 7. The intersection of the line and this plane its the center.

To find the points of tangency, find the line in the direction of (1,-2,1) that passes through the center, and find its intersection with each tangent plane.

Anonymous

Anonymous Tue 05 Apr 2022 01:30:55 No.14365328 Report

Quoted By:

Accidently posted this in the math general

I'm studying computer engineering and I am just now finishing my calculus 2 class. I have an A but only through vast amounts of practice. I am scared shitless of calc 3 and physics 1 and 2. How hard is it and what can I do to not seem totally retarded?

Anonymous

Anonymous Tue 05 Apr 2022 01:46:46 No.14365373 Report

Quoted By: >>14365699 >>14365742 >>14368375

>>14365124
How the FUCK does the series 1/n diverge but 1/n^2 converges

Anonymous

Anonymous Tue 05 Apr 2022 03:15:18 No.14365560 Report

Quoted By: >>14365724

>>14365002
you know how a 2d integral is just a 1d integral of 1d integrals?
i want to integrate over all path integrals.

Anonymous

Anonymous Tue 05 Apr 2022 04:49:37 No.14365699 Report

Quoted By:

>>14365373
The intuitive way of looking at it is that n goes to infinity too slowly, while n^2 goes to infinity fast enough for 1/n^2 to converge, in fact 1/n^r converges for any real r > 1, the threshold is right at r = 1.

Anonymous

Anonymous Tue 05 Apr 2022 05:01:36 No.14365724 Report

Quoted By: >>14365768

>>14365560
You are still describing path integrals but you only integrate once since each path is already defined over N dimensions.

Anonymous

Anonymous Tue 05 Apr 2022 05:11:03 No.14365742 Report

Quoted By:

>>14365373
What's so weird about it?

Anonymous

View Same Google iqdb SauceNAO 1640719715464.png, 2MiB, 3541x5016

Anonymous Tue 05 Apr 2022 05:11:12 No.14365743 Report

Quoted By: >>14365879

>>14362525
I'm studying Gradient Descent and just started to get into Backpropagation and i don't quite get it. Why can't i train a neural network using SGD only? What would training look like without attaching backprop to it?

Anonymous

Anonymous Tue 05 Apr 2022 05:26:23 No.14365768 Report

Quoted By:

>>14365724
im sorry, i dont follow

Anonymous

Anonymous Tue 05 Apr 2022 07:05:39 No.14365879 Report

Quoted By:

>>14365743
Naive gradient descent is inefficient and numerically unstable for a multi-layer network. Both stem from the fact that the sigmoid is intended to approximate a step function, so has a relatively steep slope in the middle of its domain.

Anonymous

View Same Google iqdb SauceNAO IMG_20220405_174013.jpg, 106KiB, 1311x983

Anonymous Tue 05 Apr 2022 07:41:59 No.14365923 Report

Quoted By: >>14366170

im expecting to get the same value for I using the 2 different methods but i get different values. Can someone explain why?

Anonymous

Anonymous Tue 05 Apr 2022 09:21:40 No.14365995 Report

Quoted By: >>14366457

>watch youtube videos
>asked upon why a specific chemical reaction occurs
>lol no one really knows
is this more common for chemistry or have I just been misled about how great our understanding of scientific subjects are

Anonymous

Anonymous Tue 05 Apr 2022 12:24:00 No.14366170 Report

Quoted By:

>>14365923
Because the integral of a product of functions doesn't work like that, as seen in integration by parts and the chain rule.
$(fg)' = f g' + f' g \Rightarrow \int (fg)' dx = \int f g' dx + \int f'g dx \neq \int f' dx \int g' dx$

$\int x^2 dx \int x^4dx = (x^3/3) (x^5/5) = x^8/15$

$\int\int x^2 x^4 dx^2 = \int\int x^6 dx^2 = \int x^7/7 dx = x^8/56$

You can see identity on the top holds
$\frac{x^3}{3}\frac{x^5}{5} = \int \frac{x^3}{3}x^4 dx + \int x^2\frac{x^5}{5}dx = \frac{x^8}{24} + \frac{x^8}{40} = \frac{x^8}{15}$

You can iterate them leaving the integration variables separate, which transforms the other integral into a constant.

$\int\int f(x)g(y) dxdy = \int f(x) G(y) dx = G(y) \int f(x) dx = G(y)F(x) = \int g(y) dy \int f(x) dx$

Anonymous

View Same Google iqdb SauceNAO ibAIGa0soD.jpg, 663KiB, 2948x1500

Anonymous Tue 05 Apr 2022 12:27:26 No.14366180 Report

Quoted By:

Want to clean my ears out, which one of these types of kits is best? Right now Im thinking about getting one like on the right vs the bottle type

Anonymous

View Same Google iqdb SauceNAO cointegration.png, 15KiB, 576x71

Anonymous Tue 05 Apr 2022 12:44:05 No.14366218 Report

Quoted By:

What are the conditions on $\phi_1$ and $\phi_2$ for the VAR(1) in the pic to be cointegrated of order 1? I know $\phi_1 = 1$ for the x part to be I(1) but I don't know how to find $\phi_2$ . I know this VAR(1) will be cointegrated if the linear combination of the 2 series is I(0).

$x_t + \alpha y_t = x_{t-1} + \phi_2 y_{t-1} + \epsilon_{1t} + \alpha(y_{t-1} + \epsilon_{2t})[\math]<br /><br />The problem is that looking at the equation it's not obvious it's even possible to choose <script type="math/tex">\alpha$ to make this an I(0). I must have a fundamental misunderstanding of the problem.

Anonymous

View Same Google iqdb SauceNAO cointegration.png, 15KiB, 576x71

Anonymous Tue 05 Apr 2022 12:45:31 No.14366222 Report

Quoted By: >>14367625

What are the conditions on $\phi_1$ and $\phi_2$ for the VAR(1) in the pic to be cointegrated of order 1? I know $\phi_1 = 1$ for the x part to be I(1) but I don't know how to find $\phi_2$ . I know this VAR(1) will be cointegrated if the linear combination of the 2 series is I(0).

$x_t + \alpha y_t = x_{t-1} + \phi_2 y_{t-1} + \epsilon_{1t} + \alpha(y_{t-1} + \epsilon_{2t})$

The problem is that looking at the equation it's not obvious it's even possible to choose $\alpha$ to make this an I(0). I must have a fundamental misunderstanding of the problem.

Anonymous

Anonymous Tue 05 Apr 2022 12:57:36 No.14366254 Report

Quoted By:

Is there on overview of the most fundamental reactions and processes in chemical industry?

Anonymous

View Same Google iqdb SauceNAO asdfawerfawes.png, 16KiB, 539x182

Anonymous Tue 05 Apr 2022 13:35:03 No.14366325 Report

Quoted By: >>14371268

What are these hats? What do they mean?

Anonymous

View Same Google iqdb SauceNAO 1620012885277.jpg, 90KiB, 594x776

Anonymous Tue 05 Apr 2022 14:50:00 No.14366442 Report

Quoted By: >>14367165 >>14367240 >>14368370

My stupid question is:
Can someone please tell me to get my butt off and study? I need someone to tell me that because I'm severely burnt out and won't get out of my bed but I need to study for the three exams tomorrow and the day after. I'm almost there...

Anonymous

Anonymous Tue 05 Apr 2022 14:57:35 No.14366457 Report

Quoted By:

>>14365995
I think sometimes the reaction is only part of a bigger picture, so if it works, it works. The application/research may have higher publishing value so they don't investigate the particular mechanism (and then forgot about it), sometimes it can be that the reaction environment may not be easily isolated or the reaction timescale is too small, so it is hard to even extract any information.
>source: me, a chemistry major that also has no idea about a lot of reactions

Anonymous

View Same Google iqdb SauceNAO self.png, 12KiB, 750x102

Anonymous Tue 05 Apr 2022 15:40:01 No.14366556 Report

Quoted By: >>14371266

If a fermionic propagator is to be interpreted as an antifermion going to a fermion, why is it that when we do a 1 loop renormalization, we consider the electron self energy, where the external states are clearly both fermions and not fermion plus an antifermion? Is it wrong to think of propagators this way?

Anonymous

View Same Google iqdb SauceNAO 6546984.png, 9KiB, 859x190

Anonymous Tue 05 Apr 2022 17:15:13 No.14366804 Report

Quoted By: >>14367278

What is the lower case Rho in this equation?
It is Rho before an (s). Are those zeros both indexes?
This is a product series so does this mean the rho(s) is only factored in during the 0th index?

https://spinningup.openai.com/en/latest/spinningup/rl_intro3.html

Anonymous

View Same Google iqdb SauceNAO 3e59eccd2ba3b993557d6ba1db636970.jpg, 115KiB, 1244x1087

Anonymous Tue 05 Apr 2022 19:28:35 No.14367165 Report

Quoted By:

>>14366442
Study.

Anonymous

Anonymous Tue 05 Apr 2022 19:58:01 No.14367240 Report

Quoted By:

>>14366442
plug off the internet cable and turn your phone off and go study

you can do it

you just need to sit for 2~8 hours and read shit, its not hard

Anonymous

Anonymous Tue 05 Apr 2022 20:14:34 No.14367278 Report

Quoted By:

>>14366804
Yes, the 0 are indexes so they are just constants brought out of the product expansion

Anonymous

View Same Google iqdb SauceNAO Capture2.png, 58KiB, 963x602

Anonymous Tue 05 Apr 2022 20:22:28 No.14367288 Report

Quoted By: >>14367290

Im confused as to what it means by features. I would use humidity and cloud cover to model

Anonymous

Anonymous Tue 05 Apr 2022 20:24:32 No.14367290 Report

Quoted By:

>>14367288
features are the parameters, it's a ML term, so in this case each column

Anonymous

Anonymous Tue 05 Apr 2022 20:34:50 No.14367305 Report

Quoted By: >>14367636

Is the following a valid statistics question:

You are rolling a 20-sided dice in a board game. The game's rules qualify the dice rolls as follows:

1-9 = Counts as Two failures
10-14 = Counts as One failure
15-19 = Counts as One success
20 = Counts as Two successes

A player starts rolling one dice at a time and wins at 16 successes. The player loses at 4 failures. What is the player's chances of winning?

Anonymous

View Same Google iqdb SauceNAO idk.png, 25KiB, 877x99

Anonymous Tue 05 Apr 2022 22:28:40 No.14367586 Report

Quoted By: >>14367630

this question is dumb i must be missing something. I am supposed to use the maximum modulus principle. i get u=Re(f(z))=(e^x)cos(y), but this doesnt satisfy the cauchy-riemann equations, and to use the maximum modulus principle it must be nonconstant and analytic in a closed region, but its not analytic. what am i missing here?

Anonymous

Anonymous Tue 05 Apr 2022 22:51:50 No.14367625 Report

Quoted By:

>>14366222
I think you just need to define $z_t = x_t + \alpha y_t$ and show that it has finite variance and autocovariances.

Anonymous

Anonymous Tue 05 Apr 2022 22:52:52 No.14367630 Report

Quoted By: >>14367681

>>14367586
You're mixing up maximus modulus for analytic functions and maximus modulus for harmonic functions.

Anonymous

Anonymous Tue 05 Apr 2022 22:54:22 No.14367636 Report

Quoted By: >>14367796

>>14367305
Yeah, it's valid.

Anonymous

Anonymous Tue 05 Apr 2022 23:25:39 No.14367681 Report

Quoted By: >>14367697

>>14367630
I might be mixing up the names, I have to use the one that says: if f is analytic and non constant in a closed region R, then the max and min of |f(z)| occur on the boundary of R. I seem to have some fundamental misunderstanding because u(x,y)=(e^x)cos(y) isn't satisfying the C-R equations but it appears to be harmonic? but something can't be harmonic and not analytic so i'm messing something up severely

Anonymous

View Same Google iqdb SauceNAO 1643528937437.png, 23KiB, 1384x1190

Anonymous Tue 05 Apr 2022 23:37:12 No.14367689 Report

Quoted By: >>14368298

I just watched a YouTube video about physics so clearly I'm an expert. Here is my theory of everything. My question is what did I do wrong?

Anonymous

Anonymous Tue 05 Apr 2022 23:39:53 No.14367697 Report

Quoted By: >>14367736

>>14367681
>I have to use the one that says: if f is analytic and non constant in a closed region R, then the max and min of |f(z)| occur on the boundary of R.
Yeah, that's the usual maximus modulus for holomorphic functions.
You can also prove that if $f$ is holomorphic and non-constant in a closed region $R$ the maximum and minimum of $Re[f(z)]$ occur on the boundary. Because $Re[f(z)]$ is harmonic.
>I seem to have some fundamental misunderstanding because u(x,y)=(e^x)cos(y) isn't satisfying the C-R equations but it appears to be harmonic? but something can't be harmonic and not analytic so i'm messing something up severely
Not sure what gave you the idea a function can't be harmonic and not analytic.
Harmonic functions are real valued (except for yada yada not relevant to you, probably won't ever be relevant to you unless you decide to do research in geometric analysis). Analytic functions are complex valued. There's no intersection.

Anonymous

Anonymous Tue 05 Apr 2022 23:54:58 No.14367736 Report

Quoted By:

>>14367697
>Not sure what gave you the idea a function can't be harmonic and not analytic.
my mistake was that i assumed the converse of: "if a function is analytic, then its real and imaginary components are harmonic" was true. analyticity implies harmonic components, but not the other way around.
Am i correct in saying that (e^x)cos(y) is not analytic? Not sure how i would proceed if it isn't analytic

Anonymous

Anonymous Wed 06 Apr 2022 00:26:07 No.14367796 Report

Quoted By: >>14367875

>>14367636
Okay. What is needed to solve such a thing? Not sure how to handle the instances that get you two successes at a time.

Anonymous

Anonymous Wed 06 Apr 2022 00:51:28 No.14367875 Report

Quoted By: >>14367956

>>14367796
>Not sure how to handle the instances that get you two successes at a time.
Monte Carlo is very reasonable for this sort of thing.
But you can grind it out.
If the player wins he either got no failures, one failure, two one failures, one two failure, three one failures or two failure and one failure.
Also, he either got 16 one successes, one two success and 14 one successes, etc. Calculate the permutations (remember they need to end in a success), multiply by the probabilities and sum.
You can do it all with some for loops.

Anonymous

Anonymous Wed 06 Apr 2022 01:20:25 No.14367956 Report

Quoted By: >>14368815

>>14367875
>Monte Carlo
I never thought of grinding it out on a computer. I always look for some kind of Distribution or Statistical Method. I'll try that.

Anonymous

View Same Google iqdb SauceNAO ballsinbins.png, 56KiB, 745x507

Anonymous Wed 06 Apr 2022 03:04:41 No.14368169 Report

Quoted By: >>14368774

>>14362525
I'm trying to apply this theorem I found in a paper to a real-world scenario. The paper is here http://www.dblab.ntua.gr/~gtsat/collection/scheduling/Balls%20into%20Bins%20A%20Simple%20and%20Tight%20Anal.pdf. Specifically I am concerned with the case where m>>n*log(n)^3. My problem is I don't know what they mean by alpha in this case. The case in question results in complex numbers for 0 > alpha > 1 and I don't understand the meaning of an alpha >1. They don't define it anywhere either in the paper. Does anyone happen to know what it might mean in this context?

Anonymous

Anonymous Wed 06 Apr 2022 04:25:25 No.14368283 Report

Quoted By:

Why isn't $\frac{\infty}{0} = 1$ or $\frac{0}{\infty} = 1$ in the Riemann Sphere or the Extended Reals?

Anonymous

Anonymous Wed 06 Apr 2022 04:31:23 No.14368298 Report

Quoted By:

>>14367689
>My question is what did I do wrong?
Nothing. Obviously.
It's nature who is wrong.

Anonymous

View Same Google iqdb SauceNAO 1648609494578.jpg, 77KiB, 900x900

Anonymous Wed 06 Apr 2022 05:17:57 No.14368370 Report

Quoted By:

>>14366442
I believe in you anon!
Get a hold of yourself!

Anonymous

Anonymous Wed 06 Apr 2022 05:21:40 No.14368375 Report

Quoted By:

>>14365373
>1/n
proof is 800 years old

Anonymous

Anonymous Wed 06 Apr 2022 05:42:53 No.14368397 Report

Quoted By: >>14368404

Let $r: A_4 \to GL_4 (\mathbb{C})$ be the standard representation of $A_4$ (defined by permutation of coordinates). Let $V = \{x \in \mathbb{C}^4 : x_1 + \dots + x_4 = 0\}$ be the orthogonal complement of $(1,1,1,1)$ . This is a 3-dimensional sub representation of $r$ . I'm trying to prove that it's irreducible.

Suppose not. Then, by Maschke, there exists a 1-dimensional sub representation of $V$ , denote it by $W$ and let it be spanned by $w \in V$ . A short argument shows that $w_i \ne 0$ for all $i=1,2,3,4$ . I think it should be possible to reach a contradiction from this, but I'm not sure what to do next.

Anonymous

Anonymous Wed 06 Apr 2022 05:55:50 No.14368404 Report

Quoted By: >>14369291

>>14368397
>A short argument shows
With similar arguments, you should also be able to show that w_i = w_j for all i and j I believe

Anonymous

Anonymous Wed 06 Apr 2022 05:59:14 No.14368405 Report

Quoted By: >>14368800

Is there a relationship between bond enthalpy and pH? I'm thinking something like hydrogen bonding would influence the bond enthalpy, but it might not be influential enough to matter

Anonymous

Anonymous Wed 06 Apr 2022 06:37:33 No.14368444 Report

Quoted By: >>14368774

How can I convert the products:
$1*4*7*10\dots (3n+1)$
$(2*3)(5*6)(8*9)\dots$
To factorial? I believe these two are related somehow

Anonymous

View Same Google iqdb SauceNAO Untitled.png, 16KiB, 468x208

Anonymous Wed 06 Apr 2022 10:00:58 No.14368667 Report

Quoted By:

I have networking problem and I'm wondering if I'm setting up the solution properly.
I want to visit as many nodes as possible and return to my starting point while minimizing cost of the traveling. My idea for the the solution is to setup a network simplex where end the node has the start nodes edge values. Would this work or am missing something?

Anonymous

View Same Google iqdb SauceNAO rotation.jpg, 81KiB, 942x354

Anonymous Wed 06 Apr 2022 10:02:05 No.14368668 Report

Quoted By:

What the hell does "looking along $/boldsymbol{a}$ from head to tail" in question b mean? Doesnt the vector go in the positive y direction?

Anonymous

View Same Google iqdb SauceNAO rotation.jpg, 81KiB, 942x354

Anonymous Wed 06 Apr 2022 10:04:48 No.14368672 Report

Quoted By: >>14368770

What the hell does "looking along $\bf{a}$ from head to tail" in question b mean? Shouldnt the vector go in the positive y direction?

Anonymous

Anonymous Wed 06 Apr 2022 11:41:51 No.14368770 Report

Quoted By:

>>14368672
>Shouldnt the vector go in the positive y direction?
Yes and looking from head to tail would be the opposite direction

Anonymous

View Same Google iqdb SauceNAO __yakumo_yukari_touhou_drawn_by_ (...).jpg, 1MiB, 1798x2862

Anonymous Wed 06 Apr 2022 11:45:05 No.14368774 Report

Quoted By: >>14369158

>>14368169
It's $k_{\alpha}$ 's argument.
Also $\alpha > 0$
>>14368444
The first one is a multifactorial.
The second one is a factorial divided by a multifactorial.

Anonymous

Anonymous Wed 06 Apr 2022 12:06:15 No.14368800 Report

Quoted By: >>14371297

>>14368405
You are asking the wrong question, but yes. There is a relationship between bond enthalpy and acid dissociation constant (Ka) which you are missing the concentration of the acid and you get pH

Anonymous

Anonymous Wed 06 Apr 2022 12:21:05 No.14368815 Report

Quoted By:

>>14367956
>>Monte Carlo
>I never thought of grinding it out on a computer. I always look for some kind of Distribution or Statistical Method.
Monte carlo is a statistical method. "Grinding it out" proper would be a brute force / computing the entire population of outcomes

Anonymous

Anonymous Wed 06 Apr 2022 14:27:18 No.14369056 Report

Quoted By: >>14371255

So I have a uraninite sample that is pretty radioactive
If I were to buy some zinc sulfide powder (the phosphor that makes tritium tubes glow) and coated my uraninite with it would it glow?
sidenote, I had to crack it in half to fit it in my container and now my desk is slightly radioactive. should I be concerned?

Anonymous

Anonymous Wed 06 Apr 2022 15:05:12 No.14369146 Report

Quoted By: >>14369493

how do I find the max angle of an oscillating pendulum given its length, mass, and height from where it's dropped?

Anonymous

Anonymous Wed 06 Apr 2022 15:09:16 No.14369158 Report

Quoted By: >>14369281 >>14369309

>>14368774
>The first one is a multifactorial.
>The second one is a factorial divided by a multifactorial.
Care to show me how can I get this result ?

Anonymous

View Same Google iqdb SauceNAO download.gif, 3KiB, 256x58

Anonymous Wed 06 Apr 2022 16:17:46 No.14369281 Report

Quoted By:

>>14369158
I think I found the product formula for the (3*2)(6*5)...
$\prod_{k=1}^{n} (3k)(3k-1)$
Wolfram told me to use the gamma function. If there a way to implement this one just using factorials exclusively?

Anonymous

Anonymous Wed 06 Apr 2022 16:20:41 No.14369291 Report

Quoted By:

>>14368404
It worked. Thanks!

Anonymous

View Same Google iqdb SauceNAO __inaba_tewi_touhou_drawn_by_kam (...).jpg, 1MiB, 1958x2195

Anonymous Wed 06 Apr 2022 16:34:26 No.14369309 Report

Quoted By: >>14369328

>>14369158
What are you talking about, it's just an immediate application of the definition.
https://mathworld.wolfram.com/Multifactorial.html

Anonymous

View Same Google iqdb SauceNAO 1649263692741.jpg, 38KiB, 480x657

Anonymous Wed 06 Apr 2022 16:48:32 No.14369328 Report

Quoted By: >>14369710

>>14369309
So, it would be something like (n)!!!? Please, explain me. I am a brainlet when it comes to math.

Anonymous

Anonymous Wed 06 Apr 2022 17:57:46 No.14369493 Report

Quoted By:

>>14369146
The mass doesn't come into it. The maximum angle is the starting angle, which is arccos((length-height)/length).

Anonymous

Anonymous Wed 06 Apr 2022 19:26:46 No.14369710 Report

Quoted By: >>14369750 >>14369755

>>14369328
Yes.

Anonymous

View Same Google iqdb SauceNAO 1649274244667.jpg, 208KiB, 850x1349

Anonymous Wed 06 Apr 2022 19:44:57 No.14369750 Report

Quoted By:

>>14369710
I think i figure out it.
$(3n+1)!!!=(3n+1)\dots 10*7*4*1<script type="math/tex"><br />I want only the elements of the sequence 3n+1 so i guess that should be alright. Now, how can I turn this one into a fraction with just single factorials. Like this for the double factorial of this function <br /><script type="math/tex">(2n-1)!!=\frac{(2n)!}{2^n*n!}$
Can I do something similar?

Anonymous

View Same Google iqdb SauceNAO 1649274418270.jpg, 208KiB, 850x1349

Anonymous Wed 06 Apr 2022 19:47:12 No.14369755 Report

Quoted By: >>14369842

>>14369710
I think i figure out it.
$(3n+1)!!!=(3n+1)\dots 10*7*4*1$
I want only the elements of the sequence 3n+1 so i guess that should be alright. Now, how can I turn this one into a fraction with just single factorials. Like this for the double factorial of this function
$(2n-1)!!=\frac{(2n)!}{2^n*n!}$
Can I do something similar?

Anonymous

Anonymous Wed 06 Apr 2022 20:29:48 No.14369842 Report

Quoted By: >>14369884

>>14369755
Why do you want to rewrite it in terms of single factorials?
You did notice that the higher the order of the multifactorial the easier it is to evaluate, right?

Anonymous

Anonymous Wed 06 Apr 2022 20:31:31 No.14369844 Report

Quoted By:

test

Anonymous

View Same Google iqdb SauceNAO word.png, 66KiB, 835x114

Anonymous Wed 06 Apr 2022 20:32:45 No.14369851 Report

Quoted By: >>14370168 >>14370196 >>14370502

Help me,I have no Idea what to do

Anonymous

Anonymous Wed 06 Apr 2022 20:44:47 No.14369884 Report

Quoted By: >>14369934

>>14369842
>Why do you want to rewrite it in terms of single factorials?
>You did notice that the higher the order of the multifactorial the easier it is to evaluate, right?
I wanto integrate a function and it happens to be that factorial function is the denomonator in power series. I think I am going to have a best chance to solve this power series.

Anonymous

Anonymous Wed 06 Apr 2022 21:03:13 No.14369934 Report

Quoted By: >>14370019

>>14369884
Right.
$n!!! (n - 1)!!! (n - 2)!!! = n!$ and so on for all the other higher multifactorials.
This formula reduces to the one you posted for $n!!$ , where you've also used $2n!! = 2^n n!$
We do have $3n!!! = 3^n n!$ , but that's not really helpful since we can't cancel out both remaining multifactorial terms.

Anonymous

View Same Google iqdb SauceNAO 0B6B0F91-F4F7-4592-83A1-494899CF (...).jpg, 297KiB, 1057x1028

Anonymous Wed 06 Apr 2022 21:16:26 No.14369982 Report

Quoted By: >>14369991 >>14370159

Can I learn Calc 1-3 in a month?

Anonymous

Anonymous Wed 06 Apr 2022 21:19:05 No.14369991 Report

Quoted By:

>>14369982
that depends entirely on how intelligent you are

Anonymous

View Same Google iqdb SauceNAO 1649280441346.jpg, 497KiB, 1484x2048

Anonymous Wed 06 Apr 2022 21:27:41 No.14370019 Report

Quoted By:

>>14369934
Thanks anon. I think I finally figure out

Anonymous

Anonymous Wed 06 Apr 2022 22:06:25 No.14370128 Report

Quoted By: >>14370262

Suppose I have a ring, such as a gyroscope, and I make this ring spin really fast so that it breaks the sound barrier. What sound would it make?

I'm thinking a popping sound, as imperfections on the surface would create bubbles that would quickly fill back the void. What do you guys think?

Anonymous

Anonymous Wed 06 Apr 2022 22:15:02 No.14370150 Report

Quoted By:

why are boltzman brains considered bad? i don't see anything wrong with brains spontaneously arranging in vacuum to feel moments of pure agony then almost instantly disintegrate.
also why is it wrong to assume that we are boltzmann brains?

Anonymous

View Same Google iqdb SauceNAO the smartest.jpg, 160KiB, 1111x1567

Anonymous Wed 06 Apr 2022 22:15:47 No.14370155 Report

Quoted By:

I keep seeing /mg/ in the catalog and thinking it's /sqt/, the joke wasn't worth it.

Anonymous

Anonymous Wed 06 Apr 2022 22:17:01 No.14370159 Report

Quoted By:

>>14369982
you can learn calc 1 and 2 in an afternoon. calc 3 is p hard tho.

Anonymous

Anonymous Wed 06 Apr 2022 22:19:35 No.14370168 Report

Quoted By: >>14370196

>>14369851
Can someone walk me through this

Anonymous

Anonymous Wed 06 Apr 2022 22:26:06 No.14370196 Report

Quoted By: >>14370283 >>14370391 >>14370541 >>14378443

>>14369851
>>14370168
Fine, fine.
The rectangle has four vertices: two at the x-axis, which we call $(x', 0), (x'', 0)$ and since it's a rectangle, the other two vertices need to be of the form $(x', y'), (x'', y')$ . These two are on the parabola, so $y' = 5 - x'^2$ and $y' = 5 - x''^2$ .
Clearly we have $x'^2 = x''^2$ and need, then, $x' = -x''$ for the rectangle to have non-zero area.
So the rectangle area is, bringing everything together, $A = 2x'y' = 2x'(5 - x'^2)$ . You're a big boy and can solve this optimization problem on your own.

Anonymous

Anonymous Wed 06 Apr 2022 22:43:35 No.14370262 Report

Quoted By: >>14370303

>>14370128
A sonic boom with an amplitude modulation with a frequency that is the same as 2x the angular frequency of the spinning ring

Anonymous

Anonymous Wed 06 Apr 2022 22:50:38 No.14370283 Report

Quoted By: >>14370310 >>14370369

>>14370196
okay I barely understood.

So a vertice is two points meeting so a rectangle has 4

Is x' the derivative of x
What is x here

Why does the vertice have the values you gave them

what is x'^2

"Clearly we have x?2=x??2 and need, then, x?=?x?? for the rectangle to have non-zero area."

I don't understand at all. how does x'^2=x''^2
Why do I need to get x'= -x''

I don't know how to calculate that I don't even know what the variables stand for

Sry this just seems very different than out other stuff so I'm lost.

Anonymous

Anonymous Wed 06 Apr 2022 22:58:20 No.14370303 Report

Quoted By: >>14370357

>>14370262
Why twice?

Anonymous

Anonymous Wed 06 Apr 2022 23:01:00 No.14370310 Report

Quoted By: >>14370369 >>14370419 >>14370594 >>14378443

>>14370283
ok, let me try:
the top two vertices have the same y value. they also are both the same distance away from the apex of the parabola (you can draw a picture to see this). the apex is at (0, 5). let $z$ be the distance along the x axis from the corners to the apex. for example, if $z=1$ , the top two corners are at (1, 4) and (-1, 4). the height of the rectangle is $f(z)$ . the width is $2z$ . the area is then $(2z)f(z)=(2z)(5-z^2)=10z-2z^3$ . find the maximum of this function on $[ 0, 5 ]$ .

View Same Google iqdb SauceNAO Double-Integral-Over-Nonrectangu (...).jpg, 28KiB, 761x206

OP Wed 06 Apr 2022 23:01:39 No.14370315 Report

Quoted By: >>14370345 >>14370400

Please help
Give a numerical answer

Anonymous

Anonymous Wed 06 Apr 2022 23:09:30 No.14370345 Report

Quoted By: >>14370441

>>14370315
Activate Windows
Go the Settings to activate Windows

Anonymous

Anonymous Wed 06 Apr 2022 23:12:29 No.14370357 Report

Quoted By: >>14370388

>>14370303
Each half of the spinning ring causes a pressure front (a sound wave), so in one complete rotation there will be two sound amplitude peaks

Anonymous

Anonymous Wed 06 Apr 2022 23:16:44 No.14370369 Report

Quoted By: >>14370377

>>14370283
>Is x' the derivative of x
No, it's just the coordinate.
Like how you call the roots of a quadratic $x'$ and $x''$ in middle school.
>>14370310
Yeah that's basically correct.

Anonymous

Anonymous Wed 06 Apr 2022 23:18:16 No.14370377 Report

Quoted By: >>14370391

>>14370369
>basically
why you always throwin shade for no fuckin reason

Anonymous

Anonymous Wed 06 Apr 2022 23:21:18 No.14370388 Report

Quoted By: >>14370446

>>14370357
So I guess it would sound something like a helicopter.

Anonymous

Anonymous Wed 06 Apr 2022 23:22:12 No.14370391 Report

Quoted By: >>14370400

>>14370377
Because you took the broad arguments in >>14370196 and diluted them down with stuff like "you can draw a picture to see this".

Anonymous

Anonymous Wed 06 Apr 2022 23:26:03 No.14370400 Report

Quoted By: >>14370409 >>14370429

>>14370391
i didnt even read your post. and being able to visualize a function in your head is the number 1, undisputable, most important skill to have in analysis. desmos can turn an extremely difficult problem into a trivially easy one. try doing >>14370315 without drawing a picture.
and its not like the guy had to prove anything, he just had to find a number.

Anonymous

Anonymous Wed 06 Apr 2022 23:28:30 No.14370409 Report

Quoted By: >>14370468

>>14370400
actually i take that one part back, its pretty easy to do that integral without drawing a picture. but you should still do it anyway for practice.

Anonymous

Anonymous Wed 06 Apr 2022 23:31:11 No.14370419 Report

Quoted By: >>14370427

>>14370310
Okay why 1 though
And I get the apex of the parabola is 5, but why is the rectangle 's vertice 4, why not 3.

Why is the height f(z)

"find the maximum of this function on [0,5]"

Like by taking the derivative of 10z-2z^3

Anonymous

Anonymous Wed 06 Apr 2022 23:33:24 No.14370427 Report

Quoted By: >>14370444 >>14378443

>>14370419
>cant do a maximum problem
ok, one step at a time. remi might disagree but i really think you should draw a picture. draw the parabola, and then draw a couple of rectangles inside of it.

Anonymous

View Same Google iqdb SauceNAO __nazrin_touhou_drawn_by_poroneg (...).jpg, 101KiB, 900x1079

Anonymous Wed 06 Apr 2022 23:33:56 No.14370429 Report

Quoted By: >>14370454

>>14370400
>being able to visualize a function in your head is the number 1, undisputable, most important skill to have in analysis
Geometric intuition that can't be transformed into clean and precise wording is hazy nonsense. We've known this since Euclid.

OP Wed 06 Apr 2022 23:38:44 No.14370441 Report

Quoted By:

>>14370345
Why? I am legally using a non-activated Windows.

Anonymous

View Same Google iqdb SauceNAO pic.png, 68KiB, 387x354

Anonymous Wed 06 Apr 2022 23:40:07 No.14370444 Report

Quoted By: >>14370454

>>14370427
It's been years since I did anything geometry related
My teacher provided us with a worked through version

Anonymous

Anonymous Wed 06 Apr 2022 23:40:42 No.14370446 Report

Quoted By:

>>14370388
Yes

Anonymous

Anonymous Wed 06 Apr 2022 23:41:51 No.14370449 Report

Quoted By:

>>14362864
1 > 1/2 + 1/4
unfortunately it will take an infinite amount of generations to make a genious again

Anonymous

Anonymous Wed 06 Apr 2022 23:42:27 No.14370454 Report

Quoted By: >>14370472 >>14370484 >>14370502 >>14370510 >>14378443

>>14370429
its much more important to see *why* something is true than to prove it using 17 layers of abstraction. how dare you discount intuition like that. we did algebra without equations for 3000 years and we did just fine.
>>14370444
good, now do you see why the width of the rectangle is $2x$ and the height is $y$ ? also this isnt geometry.

OP Wed 06 Apr 2022 23:45:28 No.14370468 Report

Quoted By: >>14370484 >>14370488

>>14370409
No one has solved this problem. But everyone says it is EASY.

Anonymous

Anonymous Wed 06 Apr 2022 23:47:14 No.14370472 Report

Quoted By: >>14370488

>>14370454
I get 2x because the rectangle crosses the y axis and x is the width from the midpoint

But I'm lost on the y. I imagine it has something to do with it being the shape of the parabola?

Anonymous

View Same Google iqdb SauceNAO 3planes1balls.jpg, 90KiB, 1920x1080

Anonymous Wed 06 Apr 2022 23:49:23 No.14370481 Report

Quoted By:

>>14363238
two planes make a line, your center can be anywhere on that line, but a line only intersects into a point on the tangent plane, so then you have your center and radius.
see pic rel

Anonymous

Anonymous Wed 06 Apr 2022 23:49:51 No.14370484 Report

Quoted By: >>14370488 >>14370494

>>14370454
>we did algebra without equations for 3000 years and we did just fine.
You need to stop appending random nonsense to the end of your arguments.
>>14370468
Evaluating integrals is boring.

Anonymous

Anonymous Wed 06 Apr 2022 23:52:12 No.14370488 Report

Quoted By: >>14370499 >>14370503 >>14370505 >>14378443

>>14370468
draw a picture :^)
ill give you a hint: the bounds of the inner integral are $y=-7x+12$ and $y=-x^2+2$ . the bounds of the outer integral are the x values where the two curves intersect.
>>14370472
the rectangle touches the parabola. the parabola has a height of $y$ .
>>14370484
you described geometry as "hazy nonsense", and i was reminding you that that was how humans did math for the majority of their existence.

OP Wed 06 Apr 2022 23:53:27 No.14370494 Report

Quoted By:

>>14370484
As long as you don't have Maple or Mathcad.

Anonymous

Anonymous Wed 06 Apr 2022 23:55:25 No.14370499 Report

Quoted By: >>14370515

>>14370488
but I thought 5 was the top of the parabola.
The rectangle my teacher drew doesn't go that high

Anonymous

Anonymous Wed 06 Apr 2022 23:57:18 No.14370502 Report

Quoted By: >>14370556

>>14369851
g(x)=2xf(x), set domain to 0 and the root, find maxima with kekulus.
>>14370454
actually area is a geometric definition, lolz

Anonymous

View Same Google iqdb SauceNAO 5b60856c71dec141f32224105e31f26be.png, 92KiB, 1106x1576

Anonymous Wed 06 Apr 2022 23:57:21 No.14370503 Report

Quoted By: >>14370515

>>14370488
>you described geometry as "hazy nonsense"
No, I described staring at drawings and deriving equalities on instinct as hazy nonsense.
Geometry is great.

View Same Google iqdb SauceNAO tttttttttttttt.jpg, 33KiB, 473x655

OP Wed 06 Apr 2022 23:58:27 No.14370505 Report

Quoted By: >>14370515

>>14370488
> bounds of the inner integral are y=?7x+12 and y=?x2+2.
My teacher said that was wrong. Why did you choose this order? After all, you could choose a different direction. See calculationss in Wolfram

Anonymous

Anonymous Thu 07 Apr 2022 00:01:12 No.14370510 Report

Quoted By: >>14370515

>>14370454
algebra is barely over 1100 years old

Anonymous

Anonymous Thu 07 Apr 2022 00:03:06 No.14370515 Report

Quoted By: >>14370524 >>14370541 >>14370556 >>14378443

>>14370499
$y$ isnt the highest point on the parabola, $y$ is a function of $x$ that tells you how high the parabola is at that specific value of $x$ . for example, at $x=0$ , the parabola is at $y=5$ , and at $x=\sqrt{5}$ , the parabola is at $y=0$ . $y$ isnt a single number, its a function.
>>14370503
well then you described what i was doing as hazy nonsense, and im equally offended. this is the stupid questions thread. i wasnt trying to show off my 1337 anal skillz, i was trying to help someone who was hopelessly lost. drawing a picture helps.
>>14370505
>Why did you choose this order?
i didnt mention any order.
>>14370510
i dont know the exact definition of algebra, but i know that the pythagorean theorem is several millennia old.

Anonymous

View Same Google iqdb SauceNAO 388-3883345_transparent-chad-png (...).png, 29KiB, 860x968

Anonymous Thu 07 Apr 2022 00:05:34 No.14370520 Report

Quoted By: >>14370562

>>14362525
Is it possible to not be a Chad yourself but reproduce Chads, or must you be a Chad? Do both parents contribute to the Chadness?

OP Thu 07 Apr 2022 00:06:34 No.14370524 Report

Quoted By: >>14370528 >>14370541

>>14370515
>i didnt mention any order
But the order is important, because the sign can be different, and the answer should be only one.

Anonymous

Anonymous Thu 07 Apr 2022 00:07:21 No.14370528 Report

Quoted By: >>14370541 >>14370559

>>14370524
oh, i see.
you want the upper bound to be the curve thats "on top" of the other curve.

Anonymous

Anonymous Thu 07 Apr 2022 00:09:29 No.14370541 Report

Quoted By:

>>14370515
>i wasnt trying to show off my 1337 anal skillz
Lad, >>14370196 is middle school argumentation.
>>14370524
The order is always counter-clockwise.
So >>14370528 for two functions.

Anonymous

Anonymous Thu 07 Apr 2022 00:16:17 No.14370556 Report

Quoted By: >>14370615

>>14370515
Okay that makes sense
How do i do a maximum problem, and what is g(x) supposed to be like this anon said
>>14370502

OP Thu 07 Apr 2022 00:16:36 No.14370559 Report

Quoted By: >>14370572

>>14370528
I want just a right number. Could you please calculate this on your software?
To compare results.

Anonymous

Anonymous Thu 07 Apr 2022 00:17:16 No.14370562 Report

Quoted By:

>>14370520
No, you can never produce a 100% pure chad from bad cloth. That's why we're tending towards total chaos and decay because chad has sex but most of his children will be virgins and then the virgins make up most of the population and chads go extinct.

Anonymous

Anonymous Thu 07 Apr 2022 00:20:41 No.14370572 Report

Quoted By: >>14370600

>>14370559
https://www.wolframalpha.com/input?i=%5Cint+_2%5E5+%5Cint_%7B-7x+%2B+12%7D%5E%7B-x%5E2+%2B+2%7D+9x+-+12y+%2B+4+dy+dx

Anonymous

Anonymous Thu 07 Apr 2022 00:26:29 No.14370594 Report

Quoted By: >>14370615

>>14370310
when you say the apex is at (0,5) you're talking about the parabola right?

And (1,4) and (1,4) is the rectangle?

View Same Google iqdb SauceNAO maf.jpg, 23KiB, 480x360

OP Thu 07 Apr 2022 00:28:13 No.14370600 Report

Quoted By:

>>14370572
Thank you. Most likely, my teacher made a mistake.

Anonymous

Anonymous Thu 07 Apr 2022 00:31:06 No.14370615 Report

Quoted By: >>14370682 >>14378443

>>14370556
$g(x)$ in that post is the area of the rectangle for different values of $x$ ( $2x$ is the width, $f(x)=y$ is the height (some functions are written like $f(x)$ , its just a different notation)).
you want to find the maximum value of $g(x)$ on $[0,\sqrt{5}]$ . $\sqrt{5}$ is chosen as the upper bound because thats where the parabola intersects the x axis, and the rectangle is supposed to be "underneath" the parabola. imagine the shape of $g(x)$ (or any function, really). the "hills" of a function are called local maxima and the "valleys" are called local minima. in both of these cases, the derivative of the function is zero, because the top of a hill and bottom of a valley is flat. its reasonable to think that the maximum value of $g(x)$ occurs at the top of a hill. so, for this problem, you should take the derivative of $g(x)$ , find the zeros, and check which zero gives the biggest value when you plug it back into $g(x)$ .
some considerations:
1) you also technically have to check $x=0$ and $x=\sqrt{5}$ as well, because those might be the highest value of $g(x)$ on the interval even though they arent technically maxima. however, its pretty easy to see that the area of the rectangle is zero in both of these cases, and the area is positive for all other values, so you could skip checking those.
2) you can tell whether or not a zero of the derivative is a hill or valley by checking the second derivative (the slope of the slope). if the second derivative is positive, then the first derivative is going from negative to positive, so its a valley. if its negative, then its a hill.
>>14370594
yeah

Anonymous

View Same Google iqdb SauceNAO word2.png, 273KiB, 834x622

Anonymous Thu 07 Apr 2022 00:52:43 No.14370682 Report

Quoted By: >>14370771 >>14370788 >>14371355

>>14370615
How do I know that
sqrt(5) is where the parobola intersects the x axis

Okay can we start over my head is starting to hurt

In my teacher's pic where does
A = 2xy come from

I get him plugging in the y

A'(x) = 10-6x^2 = 0
where does that come from

x = sqrt(5) / 3
I understand that

Then he plugs it back into the original y
and gets 10/3
I understand that

And then to get length
it's 2 * [sqrt(5) /3]

and width is 10/3

I get that

Anonymous

Anonymous Thu 07 Apr 2022 01:29:30 No.14370771 Report

Quoted By: >>14370793 >>14378443

>>14370682
>How do I know that sqrt(5) is where the parobola intersects the x axis
set $y$ to zero. $5-x^2=0$ .
>In my teacher's pic where does A = 2xy come from
thats width times height. width is $2x$ , height is $y$ .
>A'(x) = 10-6x^2 = 0
thats the derivative that you set to zero like i described.
$A(x)=(2x)(5-x^2)$
$A(x)=10x-2x^3$
$A'(x)=10-6x^2$

Anonymous

View Same Google iqdb SauceNAO a3877ab8cae7de0841d81023f0fa3e0d7.png, 108KiB, 1408x484

Anonymous Thu 07 Apr 2022 01:36:05 No.14370788 Report

Quoted By: >>14378443

>>14370682
Alright, from the start.
A rectangle has four vertices.
According to the question, two of these vertices, which we'll call $A$ and $B$ , are on the x-axis. We'll say $A = (x', 0)$ and $B = (x'', 0)$ , where $x', x''$ are as of yet unspecified real numbers.
This rectangle has two other vertices, $C$ and $D$ , which are on the parabola. Because the form is a rectangle we can choose $C = (x', y')$ ( $C$ is directly above $A$ ) and $D = (x'', y')$ (same for $D$ and $B$ , at the same height as $C$ so we can get a rectangle), where $y'$ is an unspecified real number, again.
Since $C$ is in the parabola we have $y' = 5 - x'^2$ . Similarly for $D$ we have $y' = 5 - x''^2$ . We equal both of those for $5 - x'^2 = 5 - x''^2$ . That's the same as $x'^2 = x''^2$ .
The question specifies that all two of the vertices are on the x-axis and two are above it, so $y' > 0$ , and we can use $5 - x'^2 = y' \geq 0$ to get $x'^2 \leq 5$ .
The area of the rectangle is the base ( $|x' - x''|$ ) times the height ( $y'$ ). That's only nonzero for $x' \neq x''$ , so together with $x'^2 = x''^2$ we have $x' = -x''$
Now the area is $|x ' - x''|y' = |2x'| (5 - x'^2)$ . You want to maximize that for $x'^2 < 5$ . You may assume that $x' > 0$ and then the area is $2x' (5 - x'^2)$ and the domain of maximization is $x' \in [0, \sqrt{5}]$ .

Any questions?

Anonymous

Anonymous Thu 07 Apr 2022 01:37:03 No.14370793 Report

Quoted By:

>>14370771
Okay I think I get it. I don't understand all the detail but at I should be able to get the answer on the test. Thx

Anonymous

Anonymous Thu 07 Apr 2022 03:46:51 No.14371068 Report

Quoted By: >>14371095

if you are working with live electronics then what are you supposed to do?
ground yourself or keep your feet off of the floor?
after putting screwdrivers on the stuff etc

Anonymous

Anonymous Thu 07 Apr 2022 03:58:03 No.14371093 Report

Quoted By: >>14371097 >>14371099

How do you tell north/south/west/east without a compass? What's even the the reference point?

Anonymous

Anonymous Thu 07 Apr 2022 04:00:30 No.14371095 Report

Quoted By: >>14371187

>>14371068
keep you and the circuit grounded

Anonymous

Anonymous Thu 07 Apr 2022 04:01:31 No.14371097 Report

Quoted By:

>>14371093
the sun, the stars

Anonymous

Anonymous Thu 07 Apr 2022 04:03:03 No.14371099 Report

Quoted By:

>>14371093
the sun and constellations and shit

Anonymous

Anonymous Thu 07 Apr 2022 04:53:30 No.14371187 Report

Quoted By: >>14371243

>>14371095
what if the circuit isnt

Anonymous

Anonymous Thu 07 Apr 2022 05:36:40 No.14371243 Report

Quoted By: >>14371288

>>14371187
one hand rule

Anonymous

Anonymous Thu 07 Apr 2022 05:48:05 No.14371255 Report

Quoted By:

>>14369056
most likely not, at least not nearly as bright as a tritium tube. tritium is a gas, so the emitted electrons can escape easily into the phosphor. pitchblende is a solid, so you're mostly sensitive to the emitted electrons on the surface, although you also have the benefit of multiple steps in the uranium decay chain emitting electrons. but you're fucked because the half life is much much longer than tritium for the initial alpha decay, whereas all the beta steps are relatively fast. you won't get large, concurrent emission of electrons that's required to produce something visible.
basically, you'd need special instrumentation to observe any radioluminescence, but it would technically be there.
as for your desk, it won't kill you but make sure you clean it as best you can and definitely do not eat anything that has contacted it. alpha radiation is only dangerous when consumed. beta radiation won't be produced at high enough amounts and most of it will be blocked by your clothes.

Anonymous

Anonymous Thu 07 Apr 2022 05:57:39 No.14371266 Report

Quoted By:

>>14366556
>If a fermionic propagator is to be interpreted as an antifermion going to a fermion
what? this isn't true. propagators just represent """the travel of a particle from one point to another"""

Anonymous

Anonymous Thu 07 Apr 2022 05:58:40 No.14371268 Report

Quoted By:

>>14366325
you need to specify what topic this is

Anonymous

Anonymous Thu 07 Apr 2022 06:18:25 No.14371288 Report

Quoted By:

>>14371243
left hand rule?

Anonymous

Anonymous Thu 07 Apr 2022 06:26:18 No.14371297 Report

Quoted By:

>>14368800
thanks a ton man

Anonymous

Anonymous Thu 07 Apr 2022 07:03:18 No.14371355 Report

Quoted By: >>14372270

>>14370682
>doing calculus problem
>doesn't even know calculus
>doesn't even know functions
>doesn't even know algebra
>can barely read
what third world country are you from? America? Land of the retards?

Anonymous

View Same Google iqdb SauceNAO Untitled.png, 89KiB, 939x1123

Anonymous Thu 07 Apr 2022 09:58:38 No.14371536 Report

Quoted By: >>14371552

How in the FUCK is this the answer to part (a)
Somebody please explain.

Anonymous

Anonymous Thu 07 Apr 2022 10:16:53 No.14371552 Report

Quoted By:

>>14371536
nevermind, got it.

Anonymous

View Same Google iqdb SauceNAO 1511535542845.png, 765KiB, 1280x720

Anonymous Thu 07 Apr 2022 15:46:56 No.14372237 Report

Quoted By: >>14372248 >>14372553 >>14372763

If the Earth is spinning at 1000 mph (and I don't dispute that, I'm not a retard), why don't shadows move across the ground at 1000 mph?

Anonymous

Anonymous Thu 07 Apr 2022 15:52:02 No.14372248 Report

Quoted By:

>>14372237
Which shadows?

Anonymous

Anonymous Thu 07 Apr 2022 16:05:45 No.14372270 Report

Quoted By:

>>14371355
rent free, nigger

Anonymous

Anonymous Thu 07 Apr 2022 17:56:49 No.14372553 Report

Quoted By: >>14373470

>>14372237
The speed of the shadows from a solar eclipse do move at over 1000mph. If you've ever seen an eclipse in person, and I have, it's one hell of a sight to see a wall of darkness rush towards you and then recede.

Anonymous

Anonymous Thu 07 Apr 2022 19:14:45 No.14372763 Report

Quoted By:

>>14372237
Relativity, bitch

Anonymous

Anonymous Thu 07 Apr 2022 19:25:03 No.14372798 Report

Quoted By: >>14372885 >>14372933

>T(1,1,0)=(2,1,?1)
>T(0,1,2)=(1,0,2)
>T(2,1,3)=(4,0,1)

How can I find a T of a generic (a,b,c)?

Anonymous

Anonymous Thu 07 Apr 2022 19:58:06 No.14372885 Report

Quoted By:

>>14372798
there are infinitely many solutions, all equally correct

Anonymous

Anonymous Thu 07 Apr 2022 20:08:43 No.14372916 Report

Quoted By: >>14372933

Let $\Omega \subset \mathbb{R}^n$ be open and $f: \Omega \to \mathbb{R}$ a continuous function with continuous weak derivatives $\partial_1^w f ... \partial_n^w f$ . I'm trying to prove that $f$ is $C^1$ , i.e. the $\partial_i^w f$ are classical derivatives. The hint in my book is "recall that a function with vanishing weak derivatives is constant a.e. on each connected component".

I realize I must be retarded, but how to use the hint? How does establishing the existence of $\lim_{h \to 0} \frac{f(x+he_i) - f(x)}{h}$ reduce to this?

Anonymous

View Same Google iqdb SauceNAO again.png, 86KiB, 924x255

Anonymous Thu 07 Apr 2022 20:15:59 No.14372925 Report

Quoted By: >>14372933

Okay, I get most of this, I just don't understand how
ln(1-x) gets to be in the numerator in step one.
That looks like he's multiplying rather than raising it to the power of 1/x.
Is there some rule I'm forgetting

Anonymous

View Same Google iqdb SauceNAO __hakurei_reimu_touhou_drawn_by_ (...).jpg, 548KiB, 1855x1691

Anonymous Thu 07 Apr 2022 20:17:26 No.14372933 Report

Quoted By: >>14373157 >>14373285 >>14378443

>>14372798
Is $T$ linear?
Do the ole one two.
>>14372916
You're supposed to construct a $C^1$ function such that all of the weak derivatives of $f - g$ zero.
>>14372925
$\log a^b = b \log a$

Anonymous

Anonymous Thu 07 Apr 2022 21:28:15 No.14373157 Report

Quoted By: >>14373256 >>14373267

>>14372933
>Is TT linear?
Yes. What's the ole one two?

Anonymous

Anonymous Thu 07 Apr 2022 21:48:40 No.14373256 Report

Quoted By: >>14373388

>>14373157
Find the matrix $A$ that maps $(1, 1, 0), (0, 1, 2), (2, 1, 3)$ to $(1, 0, 0), (0, 1, 0), (0, 0, 1)$ and then multiply it by the matrix that maps $(1, 0, 0), (0, 1, 0), (0, 0, 1)$ to $(2, 1, -1), (1, 0, 2), (4, 0, 1)$
The second one is trivial and the first one is matrix inversion.

Anonymous

Anonymous Thu 07 Apr 2022 21:52:11 No.14373267 Report

Quoted By: >>14373388

>>14373157
$<br />\begin{pmatrix} a_{11} & a_{12} & a_{13} \\ a_{21} & a_{22} & a_{23} \\ a_{31} & a_{32} & a_{33} \end{pmatrix} \begin{bmatrix} 1 \\ 1 \\ 0 \end{bmatrix} = \begin{bmatrix} 2 \\ 1 \\ -1 \end{bmatrix}<br />$
$<br />\begin{pmatrix} a_{11} & a_{12} & a_{13} \\ a_{21} & a_{22} & a_{23} \\ a_{31} & a_{32} & a_{33} \end{pmatrix} \begin{bmatrix} 0 \\ 1 \\ 2 \end{bmatrix} = \begin{bmatrix} 1 \\ 0 \\ -2 \end{bmatrix}<br />$
$<br />\begin{pmatrix} a_{11} & a_{12} & a_{13} \\ a_{21} & a_{22} & a_{23} \\ a_{31} & a_{32} & a_{33} \end{pmatrix} \begin{bmatrix} 2 \\ 1 \\ 3 \end{bmatrix} = \begin{bmatrix} 4 \\ 0 \\ 1 \end{bmatrix}<br />$

Anonymous

Anonymous Thu 07 Apr 2022 21:59:33 No.14373285 Report

Quoted By:

>>14372933
thx

Anonymous

View Same Google iqdb SauceNAO form.png, 156KiB, 942x530

Anonymous Thu 07 Apr 2022 22:12:26 No.14373311 Report

Quoted By: >>14373319 >>14373326

I'm working through the problems and I have no idea why 0/0 undeterminte form is off to the side. I'm able to solve it without it so I'm confused

Anonymous

Anonymous Thu 07 Apr 2022 22:16:40 No.14373319 Report

Quoted By: >>14373326 >>14378443

>>14373311
how to solve a limit:
step 1) plug in x
step 2) start doing other stuff if step 1 failed
in both problems you posted, step 1 results in 0/0

Anonymous

Anonymous Thu 07 Apr 2022 22:19:47 No.14373326 Report

Quoted By: >>14373497 >>14378443

>>14373311
Your professor is just explicitly checking the condition for using L'Hospital.
>>14373319
What the fuck are you even posting?

Anonymous

Anonymous Thu 07 Apr 2022 22:21:57 No.14373332 Report

Quoted By: >>14373411 >>14373426

I know and I understand that for someone inside a spaceship going up at 9.8ms^2 the experience should be indistinguishable than being on the surface of the Earth. But what about gravity's gradient?
The "force" of gravity affecting someone's head is lower than the "force" affecting their feet. While the acceleration felt by someone on a spaceship would be uniform right? Wouldn't that break the equivalence principle?

Anonymous

Anonymous Thu 07 Apr 2022 22:37:52 No.14373388 Report

Quoted By:

>>14373256
>>14373267
Got it. Ty.

Anonymous

Anonymous Thu 07 Apr 2022 22:50:07 No.14373411 Report

Quoted By: >>14373419 >>14373421

>>14373332
>The "force" of gravity affecting someone's head is lower than the "force" affecting their feet
A difference of 2 metres results in a ratio of 1.00000063 at the Earth's surface (a difference of 0.6 ?g) and decreases with height. It isn't something you'd notice.

For comparison, the Coriolis force from walking due North or South at 2 m/s is around 15?g, around 25 times greater.

Anonymous

Anonymous Thu 07 Apr 2022 22:54:00 No.14373419 Report

Quoted By:

>>14373411
I know that it's not something any human would be able to notice, but the problem is that there is a difference, however small, between those 2 situations right? So they shouldn't be considered "equivalent"

Anonymous

Anonymous Thu 07 Apr 2022 22:55:22 No.14373421 Report

Quoted By:

>>14373411
And? It would still be a violation of the principle.

The real answer is that the principle is local, e.g. about a point, not about the shape of the entire gravity field.

Anonymous

View Same Google iqdb SauceNAO __futatsuiwa_mamizou_touhou_draw (...).jpg, 751KiB, 1314x1148

Anonymous Thu 07 Apr 2022 22:58:42 No.14373426 Report

Quoted By: >>14373795

>>14373332
>being in a spaceship in the vacuum travelling at $9.8 ms^2$ is the same as standing on the Earth
...you're not thinking of the Einstein equivalence principle, right? Because man, you're off in the weirdest ways.

Anonymous

View Same Google iqdb SauceNAO proofs help.png, 48KiB, 892x319

Anonymous Thu 07 Apr 2022 23:16:21 No.14373459 Report

Quoted By: >>14373480 >>14373495

Im trying to learn basics of proofs, this is like the second example and i dont know what is going on.

Q1. How can she let f(1) = a? What does f(1) mean for the equation f(x+y), is it (x+y) = 1, or does y=0 and x=1? And if y is 0 doesnt that mean f(x)f(y) is f(x)*0?

Q2. How does she know that f(n) = a^n in the first place?

Pls helb, this has broken me and i am only like a paragraph in. Is this how proofs are? I feel like you have to be terrence tao to magically know that f(x)f(y) is the same as a^n

Anonymous

Anonymous Thu 07 Apr 2022 23:23:26 No.14373470 Report

Quoted By: >>14373491

>>14372553
So is my house just too small to notice that its shadow is moving at 1000 mph or something? If I were an ant, would I see shadows moving fast as hell?

Anonymous

Anonymous Thu 07 Apr 2022 23:30:34 No.14373480 Report

Quoted By: >>14373549

>>14373459
>What does f(1) mean for the equation f(x+y)
Its the function f evaluated at 1.

>is it (x+y) = 1, or does y=0 and x=1
It does not matter, since a function only depends on its parameters.

>And if y is 0 doesnt that mean f(x)f(y) is f(x)*0?
Only if f(y) would be zero.

>How does she know that f(n) = a^n in the first place?
That's the claim that is to be shown by induction.

>Is this how proofs are?
It is a very simple proof by induction.

>I feel like you have to be terrence tao to magically know that f(x)f(y) is the same as a^n
It is literally proven right there why it is the case.

That said, this whole thing is quite badly and confusingly written.

Anonymous

Anonymous Thu 07 Apr 2022 23:36:07 No.14373491 Report

Quoted By: >>14373505

>>14373470
You seem to not be understanding a basic concept here. The shadows of the house move along with the house so appear stationary.

Anonymous

Anonymous Thu 07 Apr 2022 23:37:22 No.14373495 Report

Quoted By: >>14373549

>>14373459
>Q1. How can she let f(1) = a?
You need to abstract away a little bit. There is a function f that maps from R to R with the property that f(x + y) = f(x)f(y). Naturally, this function is going to have a value when the input is 1. Saying let f(1) = a is just a shorthand way to refer to f(1). All instances of "a" in the proof could be replaced by f(1) and it wouldn't change a thing except readability.

>What does f(1) mean for the equation f(x+y), is it (x+y) = 1, or does y=0 and x=1? And if y is 0 doesnt that mean f(x)f(y) is f(x)*0

It means x+y = 1 in any possible way. This means that f(1) = f(0.5)f(0.5) = f(0.8)f(0.2) = f(1)f(0) etc. If f(0) = 0, it's quite trivial to prove that the function is 0 everywhere. However, you don't know that it is 0.

>Q2. How does she know that f(n) = a^n in the first place?
It's very important to keep in mind that understanding how a proof works is not the same as understanding why someone thought a function like this would have this property in the first place. You are reading a book on proofs, so you will likely come across examples from various fields of math.

Anonymous

Anonymous Thu 07 Apr 2022 23:38:13 No.14373497 Report

Quoted By:

>>14373326
>What the fuck are you even posting?
i was explaining why the first part of the solutions was to write down 0/0. very similar to what you posted, in fact.

Anonymous

Anonymous Thu 07 Apr 2022 23:49:08 No.14373505 Report

Quoted By: >>14373525

>>14373491
But the house is spinning with the Earth at 1000 mph, so why don't the shadows move at 1000 mph?

Fuck, I am so confused.

Anonymous

Anonymous Fri 08 Apr 2022 00:01:53 No.14373525 Report

Quoted By: >>14373544

>>14373505
>why don't the shadows move at 1000 mph?
Because the house doesn't move relatively to the earth and the angle of the sun moves very little, relatively to the earth.

Anonymous

Anonymous Fri 08 Apr 2022 00:14:30 No.14373544 Report

Quoted By:

>>14373525
>angle of the sun moves very little
THAT'S what wasn't clicking in my head! It's not the speed that matters in this case, it's the angle!

Anonymous

View Same Google iqdb SauceNAO Untitled.png, 233KiB, 772x877

Anonymous Fri 08 Apr 2022 00:18:33 No.14373549 Report

Quoted By: >>14373559 >>14373566

>>14373480
>>14373495
ty anons, super appreciate, i think i understand better now.

can you help me with this, i am confused how author knows to write it like so in the image.

its written as x = du - bv ..., but then when author shows the determinant, it becomes ud. same for cu becoming uc in the determinant for y = av - cu.

why was du and cu flipped, or rather why was it not written as ud and uc for x= and y= part.

Anonymous

Anonymous Fri 08 Apr 2022 00:22:30 No.14373559 Report

Quoted By: >>14373566

>>14373549
to clarify i mean if the determinant is a(11)*a(22)-a(12)*a(21), then shouldnt du correspond to a(11)*a(22)? the author writes it as if d is a(22) and u is a(11). if that makes sense :(

Anonymous

Anonymous Fri 08 Apr 2022 00:25:06 No.14373566 Report

Quoted By: >>14373573

>>14373549
>>14373559
you know multiplication commutes, right?

Anonymous

View Same Google iqdb SauceNAO 1635789531509.jpg, 24KiB, 590x550

Anonymous Fri 08 Apr 2022 00:31:30 No.14373573 Report

Quoted By: >>14373587

>>14373566
i thought it didnt matter, but doesnt that mess up the matrix then? du-bv implies its
d b
v u
doesnt it? the author writes du-bv as
u b
v d
which is what has me confused :(

Anonymous

View Same Google iqdb SauceNAO cursive.png, 202KiB, 910x408

Anonymous Fri 08 Apr 2022 00:36:33 No.14373586 Report

Quoted By: >>14374322 >>14374346

Can someone explain this problem to me, I don't know cursive :(

Anonymous

Anonymous Fri 08 Apr 2022 00:37:20 No.14373587 Report

Quoted By: >>14373623

>>14373573
Both determinants are equivalent...

The author is describing the Cramer's rule, and the "true" way to write the determinant is the one in the bottom, because the matrices in the Cramer's rule take the column vectors of the system as columns. However, when doing the calculation, who cares if you write d first or u first? You are being way too rigid.

Anonymous

Anonymous Fri 08 Apr 2022 00:53:55 No.14373623 Report

Quoted By:

>>14373587
>cramers rule
tyvm anon, i didnt know it was a special thing

Anonymous

View Same Google iqdb SauceNAO 1645816483626.png, 955KiB, 753x707

Anonymous Fri 08 Apr 2022 01:31:03 No.14373713 Report

Quoted By: >>14374771

Are any of you guys good at differential equations? I'm getting stuck on this problem:

Solve using the Laplace Transform:

y' + 7y = f(t)

y(0) = 0 where f(t) = 0 for 0 ? t < 2 and f(t) = 4 for t ? 2

Anonymous

Anonymous Fri 08 Apr 2022 02:02:53 No.14373795 Report

Quoted By: >>14374901

>>14373426
isnt that how it works

Anonymous

View Same Google iqdb SauceNAO Screenshot 2022-04-08 at 04.55.04.png, 118KiB, 728x503

Anonymous Fri 08 Apr 2022 03:02:30 No.14374065 Report

Quoted By: >>14374075

How is $n\cdot ln(1+\frac{7}{n}) = \frac{ln(1+7n)}{n}$

Anonymous

Anonymous Fri 08 Apr 2022 03:05:54 No.14374075 Report

Quoted By:

>>14374065
Nevermind I think I was just a retard when I noted this down 9 years ago.
Reading through old notes was a mistake.

Anonymous

Anonymous Fri 08 Apr 2022 04:17:29 No.14374322 Report

Quoted By:

>>14373586
pls

Anonymous

Anonymous Fri 08 Apr 2022 04:25:22 No.14374346 Report

Quoted By: >>14374401 >>14378443

>>14373586
Do you know what the Mean Value Theorem is?

Anonymous

Anonymous Fri 08 Apr 2022 04:39:42 No.14374401 Report

Quoted By:

>>14374346
No, I'm looking at a organic chem teacher vid rn on the matter but I'm tired and it seems to be more simple than what my teacher is askig

Anonymous

Anonymous Fri 08 Apr 2022 06:06:30 No.14374549 Report

Quoted By: >>14374564

Do two bodys with the same mass but hugely diferent volumes create the same curve in space?

i mean like a basquetball with the mass of the sun type of thing

Anonymous

Anonymous Fri 08 Apr 2022 06:17:12 No.14374564 Report

Quoted By: >>14374616

>>14374549
At a far enough distance the gravitational effect (curvature) would be essentially identical, i.e. Newton's law, but locally to each mass the curvature would be different.

Anonymous

Anonymous Fri 08 Apr 2022 06:53:26 No.14374616 Report

Quoted By: >>14374711

>>14374564
Close but not quite, they are exactly the same, assuming homogeneous mass distribution. It's called a point mass.

Anonymous

Anonymous Fri 08 Apr 2022 07:46:43 No.14374711 Report

Quoted By: >>14374756

>>14374616
That can't be true. Take two 1000kg mass spheres. One 1m in radius, the other 1km. Now what's the curvature at a point 0.5km for each center of mass?

Anonymous

Anonymous Fri 08 Apr 2022 07:58:03 No.14374724 Report

Quoted By: >>14374779

i have a data set which consists of +1s and -1s arranged in 4x4 arrays with spaces after each array. How do i plot squares in two different colors (one square for one 1) for the plus 1s and minus 1s in gnuplot? Im just trying to do some monte carlo stuff for the ising model and wanted to plot the spin configurations.

Anonymous

Anonymous Fri 08 Apr 2022 08:27:07 No.14374756 Report

Quoted By: >>14374776

>>14374711
The same? Which part of curvature depends on matter and not mass?

Anonymous

Anonymous Fri 08 Apr 2022 08:39:11 No.14374771 Report

Quoted By:

>>14373713
sY(s)-y(0) + 7Y(s) = F(s)
=> (s+7)Y(s) = F(s)
=> Y(s) = F(s)/(s+7) = 4e^(-2s) / s(s+7)
= 4e^(-2s) (1/7s - 1/7(s+7))
= (4/7) e^(-2s) (1/s - 1/(s+7))
=> y(t) = (4/7) u(t-2) (1 - e^(-7(t-2)))

Anonymous

Anonymous Fri 08 Apr 2022 08:42:38 No.14374776 Report

Quoted By: >>14374798 >>14374814

>>14374756
A uniform sphere only behaves like a point mass outside the sphere. Once you get inside the sphere, gravity decreases with radius rather than being inverse-square.

Anonymous

Anonymous Fri 08 Apr 2022 08:44:06 No.14374779 Report

Quoted By: >>14374804

>>14374724
LibreOffice conditional format? Sorry I don't use gnuplot.

Anonymous

Anonymous Fri 08 Apr 2022 09:06:56 No.14374798 Report

Quoted By:

>>14374776
I think you are talking about a hollow sphere, which follows Gauss law i.e. flux through the surface. For a solid mass you apply inverse square law with point mass.

Anonymous

Anonymous Fri 08 Apr 2022 09:09:27 No.14374804 Report

Quoted By: >>14374825

>>14374779
the data set is just a text file also can you recommend a way to generate the plot i mentioned?

Anonymous

View Same Google iqdb SauceNAO file.png, 216KiB, 757x1197

Anonymous Fri 08 Apr 2022 09:09:41 No.14374805 Report

Quoted By:

>>14362525
How do I do part b) and c)???

Anonymous

Anonymous Fri 08 Apr 2022 09:18:00 No.14374814 Report

Quoted By: >>14374842

>>14374776
If you start digging towards the center of the earth what happens? It's not going to be linear. Nobody has ever claimed that.

Anonymous

View Same Google iqdb SauceNAO Capture.png, 38KiB, 921x534

Anonymous Fri 08 Apr 2022 09:26:27 No.14374825 Report

Quoted By: >>14374869

>>14374804
like this?

Anonymous

Anonymous Fri 08 Apr 2022 09:39:41 No.14374842 Report

Quoted By:

>>14374814
gravity will go down as the mass is cancelling out on the other side, at the center all mass would cancel out, i dont know if it's actually linear though.

Anonymous

Anonymous Fri 08 Apr 2022 09:56:18 No.14374869 Report

Quoted By:

>>14374825
oh shit yeah like that

Anonymous

View Same Google iqdb SauceNAO __kirisame_marisa_touhou_drawn_b (...).jpg, 330KiB, 1549x2180

Anonymous Fri 08 Apr 2022 10:11:05 No.14374901 Report

Quoted By:

>>14373795
I was hoping you'd reread the EEP and tell on your own, but it's for free falling bodies. Standing on the earth isn't free falling. Being in an accelerating spaceship is also not free falling.
Also, the experiment needs to be non-gravitational, which means that gravitational field inhomogeneities need to be negligible comparable to whatever you're measuring, including in particular gravitational interactions between the particles in the experiment.

Anonymous

View Same Google iqdb SauceNAO Screenshot 2022-04-08 at 12.16.13.png, 22KiB, 544x198

Anonymous Fri 08 Apr 2022 10:20:06 No.14374922 Report

Quoted By: >>14375179 >>14375226

I'm dumb. How would I go about solving this? I don't see polar coordinates helping and don't know where to start using the squeeze theorem here.

Anonymous

Anonymous Fri 08 Apr 2022 11:45:09 No.14375179 Report

Quoted By: >>14375226

>>14374922
Would it be wrong to use small angle approximation here?

Anonymous

Anonymous Fri 08 Apr 2022 11:56:00 No.14375226 Report

Quoted By:

>>14374922
>>14375179
Not really, but you're basically using L'Hospital.

Anonymous

Anonymous Fri 08 Apr 2022 12:50:23 No.14375384 Report

Quoted By: >>14375680

I'm using numpty in python.
I've created a really long list.
I've created an empty array of equal length.
How the FUCK do I just assign each item in the list to the corresponding index of the array?

Anonymous

View Same Google iqdb SauceNAO Smoking-can-make-you-impotent.jpg, 87KiB, 960x960

Anonymous Fri 08 Apr 2022 14:41:26 No.14375671 Report

Quoted By:

I have a medical question that I hope isn't too stupid. Does anyone know whether there's any data showing if nicotine damage on penile blood vessels in reversible?

>nicotine treatment has deleterious effects on vascular functioning and catecholamine modulation, which may compromise erectile functioning
>https://pubmed.ncbi.nlm.nih.gov/17971108/

I can find quite a bit of data regarding the long term and short term effects of smoking on erectile function but other than the article above I find few that discuss smokeless, tobacco-less products like nicotine pouches or lozenges. I smoked for a year and a half when I was in the military and then quit and began using smokeless tobacco for a few months, followed by tobacco-less alternatives. I've noticed an increasing inability to sexually perform and thought it was due to pornography or lack of exercise, both of which I've increased, I've improved my diet, and when I went to my doctor he said the main thing has to be the nicotine. He wanted to start me out on sildenafil but I don't want to be on meds with side effects like that - is there hope that, quitting nicotine completely starting yesterday, my blood vessels will eventually recuperate?

Anonymous

Anonymous Fri 08 Apr 2022 14:42:08 No.14375674 Report

Quoted By: >>14375704 >>14375895

can someone explain how e^-x becomes x

Anonymous

Anonymous Fri 08 Apr 2022 14:44:27 No.14375680 Report

Quoted By:

>>14375384
y[:]=x or y[...]=x
You have to assign to a slice because y=x will just rebind the name y to refer to the list.

Anonymous

View Same Google iqdb SauceNAO e.png, 189KiB, 911x391

Anonymous Fri 08 Apr 2022 14:49:44 No.14375704 Report

Quoted By: >>14375895

>>14375674
sry forgot pic

Anonymous

Anonymous Fri 08 Apr 2022 15:33:00 No.14375895 Report

Quoted By: >>14375907 >>14378443

>>14375674
>>14375704
I assume you mean $e^{-x}(2x-x^2)$ to $x(2-x)$ part. he just skipped some steps. $2x-x^2$ is factorized to $x(2-x)$ and since $e^{-x}$ only approaches 0 when x = infinity, it can be ignored for f'(x)=0.

Anonymous

Anonymous Fri 08 Apr 2022 15:35:23 No.14375907 Report

Quoted By:

>>14375895
Oh (2-x) is factored, I don't know why but I thought that was a derivative of 2x-x^2

Anonymous

View Same Google iqdb SauceNAO INFLECTION.png, 120KiB, 795x343

Anonymous Fri 08 Apr 2022 15:52:37 No.14376005 Report

Quoted By: >>14376023 >>14376057 >>14376072

For the inflection points, do I plug in the x values to the original function or the derivative

Anonymous

Anonymous Fri 08 Apr 2022 15:59:14 No.14376023 Report

Quoted By: >>14378443

>>14376005
The inflection point candidates are the roots of the second derivative.
You then check whether or not the second derivative actually changes sign when passing the inflection point.

Anonymous

Anonymous Fri 08 Apr 2022 16:07:22 No.14376057 Report

Quoted By: >>14378443

>>14376005
original function. You are trying to find the the "y-coordinate" after finding out the x from second derivatives.

Anonymous

Anonymous Fri 08 Apr 2022 16:11:11 No.14376072 Report

Quoted By: >>14378443

>>14376005
Third derivative. An inflection point is a point where the second derivative changes sign. I.e. if f''(x)=0 and the next-highest derivative which is non-zero at the point is an odd derivative.

If the second derivative is zero and the next-highest non-zero derivative is an even derivative, it means that the second derivative goes positive-zero-positive or negative-zero-negative rather than changing sign.

Anonymous

Anonymous Fri 08 Apr 2022 17:24:28 No.14376317 Report

Quoted By: >>14376351

>>14362525
I can sample from the posterior of a mixture of N gaussians, each with weight w_i by first sampling a normal distribution with weights (w_i, i=1:N) en than sampling from N(\mu_i, \sigma_i).
But can I also sample from all N normal distributions and take the (w_i) weighted average?

Anonymous

Anonymous Fri 08 Apr 2022 17:38:22 No.14376351 Report

Quoted By:

>>14376317
nvm mixture of pdfs is different than sum of gaussians

Anonymous

Anonymous Fri 08 Apr 2022 18:02:25 No.14376428 Report

Quoted By: >>14376589

I am creating a plot of revenues in constant dollars over time, 2001-2021. Is there a convention on whether values should be given in 2001 dollars, or 2021 dollars?

Anonymous

Anonymous Fri 08 Apr 2022 18:58:41 No.14376589 Report

Quoted By:

>>14376428
You use the value for the present day, since that is what people are most familiar with, and then state that all earlier prices have been adjusted for inflation.

Anonymous

Anonymous Fri 08 Apr 2022 19:27:42 No.14376660 Report

Quoted By: >>14376734

How can I show every 3-dimensional Lie algebra is either simple or solvable? It seems like it should be easy

Anonymous

Anonymous Fri 08 Apr 2022 19:47:37 No.14376734 Report

Quoted By: >>14376812 >>14376824

>>14376660
Either $[g, g] = g$ or it's solvable (because all of the bidimensional Lie algebras are solvable).
Figure it out from there.

Anonymous

Anonymous Fri 08 Apr 2022 20:10:13 No.14376812 Report

Quoted By: >>14376824

>>14376734
Ok, I was taking a totally different approach. I've shown no simple Lie algebra is solvable, regardless of dimension. Now I want to show if L is not simple and dim(L)=3, it must be solvable. Is this true? Or am I retarded

Anonymous

Anonymous Fri 08 Apr 2022 20:14:29 No.14376824 Report

Quoted By:

>>14376812
>>14376734
nvrmind I think I figured it out, you use the quotient property (I, L/I solv -> L solv). Thanks.

Anonymous

View Same Google iqdb SauceNAO Capture.png, 79KiB, 1330x663

Anonymous Fri 08 Apr 2022 20:31:52 No.14376894 Report

Quoted By: >>14377065 >>14377305 >>14377310

I dont really understand what i need to do to display how many species there are (Python)

Anonymous

Anonymous Fri 08 Apr 2022 21:35:36 No.14377065 Report

Quoted By: >>14377067 >>14377096

>>14376894
(Iterate through the first column in every row)
if first == "penguins" nunofpenguins += 1

print numofpenguons

Anonymous

Anonymous Fri 08 Apr 2022 21:36:07 No.14377067 Report

Quoted By:

>>14377065
>>>/g/

Anonymous

View Same Google iqdb SauceNAO Capture2.png, 28KiB, 1390x262

Anonymous Fri 08 Apr 2022 21:48:49 No.14377096 Report

Quoted By: >>14377314

>>14377065
thank you

this is the last thing i need help with. I really dont know what documentation i need to look at so that i can add color to each specific penguin type.

Anonymous

View Same Google iqdb SauceNAO 1645756994316.jpg, 9KiB, 225x225

Anonymous Fri 08 Apr 2022 22:47:42 No.14377255 Report

Quoted By: >>14377290

Can someone give me some simple to understand example of how learning all the math helps with programming?

Those coding bootcamps dont teach any math do they?

Anonymous

Anonymous Fri 08 Apr 2022 23:04:06 No.14377290 Report

Quoted By:

>>14377255
Ability to learn the math implies high general intelligence. High general intelligence means learning and understanding programming is much easier.

Anonymous

Anonymous Fri 08 Apr 2022 23:09:56 No.14377305 Report

Quoted By: >>14377314

>>14376894
VC = dict(penguins_df['species'].value_counts())
VC['Adelie']
VC['Gentoo']
VC['Chinstrap']

Anonymous

Anonymous Fri 08 Apr 2022 23:12:34 No.14377310 Report

Quoted By: >>14377314

>>14376894
If you're looking for the number of unique species (as your text asks)
len(set(penguins_df['species']))

Anonymous

View Same Google iqdb SauceNAO Capture3.png, 99KiB, 1412x724

Anonymous Fri 08 Apr 2022 23:14:05 No.14377314 Report

Quoted By: >>14377319 >>14377326 >>14377337

>>14377096
>>14377310
>>14377305
i got it, thank you

ive been stcuk on this one for the past two hours though, I just dont understand how am i supposed to color code it using the species

Anonymous

Anonymous Fri 08 Apr 2022 23:15:57 No.14377319 Report

Quoted By: >>14377479

>>14377314
Define a legend? Overlay multiple plots of partitioned data?
Really can't come up with one solution yourself? Have you tried googling it?

Anonymous

Anonymous Fri 08 Apr 2022 23:18:25 No.14377326 Report

Quoted By: >>14377479 >>14377493

>>14377314
Which of the 3 methods did you find best? What did you learn from them? Are you trying to learn methods and use optimal approaches or just trying to get homework done?

Anonymous

View Same Google iqdb SauceNAO __remilia_scarlet_and_flandre_sc (...).jpg, 809KiB, 2200x3504

Anonymous Fri 08 Apr 2022 23:25:25 No.14377337 Report

Quoted By: >>14377479

>>14377314
According to the documentation in https://matplotlib.org/3.5.0/api/_as_gen/matplotlib.pyplot.scatter.html , I think you just need to:
>define a dict storing the colour for each penguin species
>iterate through the original list to build a list with the colour for each entry in order
>pass it in as the c argument to plt.scatter

Anonymous

Anonymous Sat 09 Apr 2022 00:38:23 No.14377479 Report

Quoted By: >>14377549

>>14377319
I have tried googling it,
>>14377326
this is an intro engineering class and one part of it is programming. No prior coding experience was required for the class and they threw python at us for us to figure out. Which i dont mind but i need a proper anchor point. i think the point of the class is to expose us to this stuff now so later we'll pick up on it a bit faster when we actually take classes on specific topic. Next semester ill be taking a proper engineering programming class. I couldnt take it this semester without taking the one im in now.

as a result of all this i have no idea what any of this means>>14377337

I only udnerstand bits and pieces of it

Anonymous

View Same Google iqdb SauceNAO Capturr323e.png, 3KiB, 529x76

Anonymous Sat 09 Apr 2022 00:45:04 No.14377493 Report

Quoted By: >>14377537 >>14377555

>>14377326
oh and to answer your question i found out i could do something else for the first one (in pic)

I am genuinely trying to learn it but understand today is my first day with python so forgive me for not understand the syntax immediately

Anonymous

View Same Google iqdb SauceNAO 1640247842475.jpg, 1MiB, 1062x1420

Anonymous Sat 09 Apr 2022 00:52:02 No.14377509 Report

Quoted By: >>14377586

how do i cure anhedonia?

Anonymous

View Same Google iqdb SauceNAO Capture2312.png, 82KiB, 1351x654

Anonymous Sat 09 Apr 2022 01:12:07 No.14377537 Report

Quoted By: >>14377555 >>14377571

>>14377493
welp my dumbass finally figured it out

Anonymous

Anonymous Sat 09 Apr 2022 01:21:46 No.14377549 Report

Quoted By:

>>14377479
Just checking if you even care about the solutions. Seemed like you were dismissing all the others because you have a number you like. Homework posts are bannable offenses so wondering if that's all it was

Anonymous

Anonymous Sat 09 Apr 2022 01:24:05 No.14377555 Report

Quoted By:

>>14377493
>>14377537
Yeah always a show learning process and you'll find across many different optimal methods to solve the same problem (optimal computation time or memory or code writing etc)
Always hated formatting plots. 10 seconds to make a plot from data, 5 hours to make it look pretty and publishable

Anonymous

View Same Google iqdb SauceNAO __hakurei_reimu_and_remilia_scar (...).jpg, 1016KiB, 1400x991

Anonymous Sat 09 Apr 2022 01:30:38 No.14377571 Report

Quoted By:

>>14377537
I knew you could do it.
I didn't know you could call .map directly with a dict, that's neat.

Anonymous

Anonymous Sat 09 Apr 2022 01:38:35 No.14377586 Report

Quoted By:

>>14377509
stop doing drugs and let yourself feel depressed for months. your neurochemistry should reset in about 6 months. i'm serious about saying that you should stop doing all drugs, that includes sugar, tobacco, and masturbation. allow the daily surprises of life be the only joy you receive, and after a while you won't be so mentally fucked.

Anonymous

View Same Google iqdb SauceNAO __flandre_scarlet_touhou_drawn_b (...).jpg, 822KiB, 900x1250

Anonymous Sat 09 Apr 2022 10:51:49 No.14378440 Report

Quoted By:

>>14362929
you are her food

Anonymous

Anonymous Sat 09 Apr 2022 10:53:38 No.14378443 Report

Quoted By:

>>14370196
>>14370310
>>14370427
>>14370454
>>14370488
>>14370515
>>14370615
>>14370771
>>14370788
>>14372933
>>14373319
>>14373326
>>14374346
>>14375895
>>14376023
>>14376057
>>14376072
Thx for the help eveyone but I'm pretty sure I just failed the test, gonna have to drop see you back in the summer

Anonymous

View Same Google iqdb SauceNAO __patchouli_knowledge_touhou_dra (...).jpg, 729KiB, 960x1280

Anonymous Sat 09 Apr 2022 15:32:49 No.14379186 Report

Quoted By: >>14379476

What's the deal with /scg/ reusing the same OP image every thread? Am I the only one who finds it jarring?

Anonymous

Anonymous Sat 09 Apr 2022 15:59:49 No.14379255 Report

Quoted By:

I'm looking for an article I read years ago and the associated paper. It described a way to induce the photovoltaic effect in materials that don't normally exhibit it. I think they used strips of graphene over a conductor and then ran a current through the graphene to start the effect which would sustain itself. I think it said the panels achieved something like a 10% efficiency. Every so often I try to find this article, but there's so much being written about solar every day that I can never find it.

Anonymous

Anonymous Sat 09 Apr 2022 16:22:54 No.14379308 Report

Quoted By: >>14379777

I got curious and was wondering for what f(x) $\displaystyle \int f(x)^{dx} = e^{\int \ln(f(x))dx} = \int f(x) dx$

Does anyone knows if there is an answer?

Anonymous

Anonymous Sat 09 Apr 2022 17:37:13 No.14379476 Report

Quoted By: >>14379727

>>14379186
i thought you were the one doing it.
i think its fine, cant have every thread op be cute anime girls.

Anonymous

View Same Google iqdb SauceNAO __cirno_touhou_drawn_by_aizetton (...).jpg, 187KiB, 1507x1391

Anonymous Sat 09 Apr 2022 18:50:33 No.14379727 Report

Quoted By: >>14380354

>>14379476
No, I only make it whenever someone asks here or when I notice there isn't one in the catalog.
>cant have every thread op be cute anime girls.
Whenever I do make an /scg/ I eenie meenie some image from the previous thread.
It's a very simple process for finding an on-topic image.

Anonymous

Anonymous Sat 09 Apr 2022 19:01:52 No.14379777 Report

Quoted By:

>>14379308
0

Anonymous

View Same Google iqdb SauceNAO file.png, 1MiB, 1280x720

Anonymous Sat 09 Apr 2022 20:55:47 No.14380287 Report

Quoted By: >>14380328

I did some stupid thing with my equipment.
>tuner pedal needs 18V 1A
>have been using it for months connected to 18V 500mA
Was I lucky that it was less mA than rated? If it was over 1A would the pedal be kill?

Anonymous

Anonymous Sat 09 Apr 2022 21:08:07 No.14380328 Report

Quoted By: >>14380333

>>14380287
the amperage of a voltage supply is the *maximum* current that it can deliver. so, if the pedal needs 1 amp, you could use a 2 amp supply just fine. a 500mA supple might cause issues, but its unlikely to permanently damage anything.

Anonymous

Anonymous Sat 09 Apr 2022 21:09:56 No.14380333 Report

Quoted By: >>14380335

>>14380328
So the volts is the value that can kill pedals if you go over?

Anonymous

Anonymous Sat 09 Apr 2022 21:10:35 No.14380335 Report

Quoted By: >>14380353

>>14380333
yeah.

Anonymous

Anonymous Sat 09 Apr 2022 21:15:25 No.14380353 Report

Quoted By:

>>14380335
Thanx. It's alright since I only use it as a tuner even though it's also a power pedal.

Anonymous

View Same Google iqdb SauceNAO 32f67012196d6315d1e47f33048c09bf.png, 2MiB, 1600x1600

Anonymous Sat 09 Apr 2022 21:15:33 No.14380354 Report

Quoted By:

>>14379727
nice job posting a cirno on the 9th

Anonymous

Anonymous Sat 09 Apr 2022 21:16:02 No.14380355 Report

Quoted By: >>14380406

I want to learn a 4 year degrees worth of math in half a year
Can I do it?

Anonymous

View Same Google iqdb SauceNAO set.png, 54KiB, 764x71

Anonymous Sat 09 Apr 2022 21:17:11 No.14380359 Report

Quoted By: >>14380371

How does this set have 16 subsets? I count 13:
6, 7, 8, 9
67, 68, 69
78, 79
89
678, 789
0

Anonymous

View Same Google iqdb SauceNAO __houjou_satoko_higurashi_no_nak (...).jpg, 2MiB, 2000x2000

Anonymous Sat 09 Apr 2022 21:20:42 No.14380371 Report

Quoted By: >>14380394

>>14380359
K has 4 elements. for each subset, each of the 4 elements either is or isnt in the subset, so there are $2^4=16$ subsets.

Anonymous

View Same Google iqdb SauceNAO 1640263568041.jpg, 104KiB, 1065x1064

Anonymous Sat 09 Apr 2022 21:27:36 No.14380394 Report

Quoted By:

>>14380371
ty anon

i forgot 689 and 679, and 6789, which they even mention in the example as K itself.

Anonymous

View Same Google iqdb SauceNAO 7c5101929a5cabad365f2515a72a2bd7.jpg, 3MiB, 3024x4032

Anonymous Sat 09 Apr 2022 21:31:54 No.14380406 Report

Quoted By:

>>14380355
Yes. They go really slow paced in undergrad. Just pick up the recommended textbook one-by-one and start working from morning to evening every day and you'll be there. For any undergrad topic there's usually lectures if the book stops making sense.

Anonymous

View Same Google iqdb SauceNAO 41241581245.png, 571KiB, 546x626

Anonymous Sun 10 Apr 2022 01:17:47 No.14381021 Report

Quoted By: >>14381039

how is (-8,5) a subset of (-2,6)?

i thought a subset is: A is a subset of B if every element of A is also in B.

how is -8 in the range of -2 to 6?

Anonymous

Anonymous Sun 10 Apr 2022 01:23:54 No.14381039 Report

Quoted By: >>14381050

>>14381021
That's a weird filename.
Also, it's not a subset. Typo in your book or something.

Anonymous

View Same Google iqdb SauceNAO Untitled.png, 348KiB, 1112x588

Anonymous Sun 10 Apr 2022 01:26:23 No.14381050 Report

Quoted By: >>14381053 >>14381060 >>14381101

>>14381039
ty anon, are any others wrong?

Anonymous

Anonymous Sun 10 Apr 2022 01:27:47 No.14381053 Report

Quoted By: >>14381060

>>14381050
actually i forgot to ask, why is e) and j) false?

Anonymous

Anonymous Sun 10 Apr 2022 01:30:22 No.14381060 Report

Quoted By: >>14381076

>>14381050
a is very contextual.
If I saw the question on a test I'd just write "Go fuck yourself" on my answer.
g is true.
>>14381053
>e
Because $2.5 \in [2, 5]$ but $2.5 \notin \{2, 3, 4, 5\}$
>j
Guess.

Anonymous

Anonymous Sun 10 Apr 2022 01:35:18 No.14381076 Report

Quoted By: >>14381089

>>14381060
tyvm anon, so [7,10] is not a subset of {7,8,9,10} because you can have numbers like 7.5

and if e was written as {2, ... , 5} would [2, 5] then work?

Anonymous

Anonymous Sun 10 Apr 2022 01:40:59 No.14381089 Report

Quoted By: >>14381097

>>14381076
>{2, ... , 5}
Not really.
I get what you mean, but in mathematics stuff like $a, \ldots, b$ is taken to imply there are only finitely many terms between $a$ and $b$ , so most people would either read $\{2, \ldots, 5\}$ as $\{2, 3, 4, 5\}$ or not infer anything at all.
Which is different from $\ldots<script type="math/tex"> not followed by anything. That implies countably many terms.$

Anonymous

Anonymous Sun 10 Apr 2022 01:43:12 No.14381095 Report

Quoted By:

How do I get a lot of updoots on MSE

Anonymous

View Same Google iqdb SauceNAO 3141592653588.png, 223KiB, 309x292

Anonymous Sun 10 Apr 2022 01:43:43 No.14381097 Report

Quoted By:

>>14381089
oh okay tyvm

Anonymous

Anonymous Sun 10 Apr 2022 01:44:32 No.14381101 Report

Quoted By: >>14381116 >>14381162 >>14381317

>>14381050
(a) Depends on how you construct the natural numbers.
(b) False. The operation of multiplication over the complex numbers is closed, meaning that you still get a complex number even if the imaginary part is zero. However, some people might refer to an element of the set of complex numbers as a "real number" if they're speaking loosely.
(c) False; see (b). The rationals are constructed in terms of the integers but do not actually contain elements of the set of integers.
(d) False by any understanding.
(e) Unlikely. [2,5] usually refers to the set elements between the real numbers 2 and 5 (inclusive). Even if it referred to a similar set over the natural numbers, {2,3,4,5} may be a subset of the reals, the complex numbers, the rationals, etc.
(f) - (l) See (e).
(m) True.

Anonymous

View Same Google iqdb SauceNAO __hakurei_reimu_touhou_drawn_by_ (...).jpg, 1MiB, 1500x1500

Anonymous Sun 10 Apr 2022 01:52:33 No.14381116 Report

Quoted By: >>14381162 >>14381173 >>14381254

>>14381101
If you're going to be pedantic at least be pedantic correctly.
>b
Depends on how the real and complex numbers are constructed.
>c
Depends on how the integers and rational numbers are constructed.
>d
Depends on how the integers and rational numbers are constructed.

Anonymous

Anonymous Sun 10 Apr 2022 02:13:39 No.14381162 Report

Quoted By: >>14381254

>>14381101
>>14381116
ty anons, i thought for b) its true because it says if you multiply a complex number by its conjugate it becomes a real number. it says (a+bi)*(a-bi) = a^2 + b^2

Anonymous

Anonymous Sun 10 Apr 2022 02:18:44 No.14381173 Report

Quoted By: >>14381254

>>14381116
also what does "how the real and complex numbers are constructed" mean?

is this a higher level math thing?

i am starting the book "a transition to advanced math"

Anonymous

Anonymous Sun 10 Apr 2022 02:47:05 No.14381245 Report

Quoted By: >>14381334

What should I expect to learn in a undergrad course on artificial intelligence?

Anonymous

Anonymous Sun 10 Apr 2022 02:50:51 No.14381254 Report

Quoted By: >>14381472

>>14381116
I mean you can go pretty deep with pedantry, but there's a difference between asking "how is the word 'Apple' defined" and "how is the letter 'A' defined."
To be more direct to your comments: I don't know of any real and complex number constructions which would have multiplication on the set of complex numbers mapping to another set, or one for which the real numbers are a subset of the complex numbers. You could certainly make that construction but it would probably be novel. Likewise for the rationals and integers.
>>14381162
You should probably put "true." While you get a complex number, it's almost certain that the assignment is expecting you to be less rigorous and say it's a real number. Consider that I may refer to a single number 2 as the natural number 2, the integer 2, the rational 2, etc. The set that 2 corresponds to (yes, "2" is a set itself) depends on the set that it is from. Again, when speaking less rigorously, all numbers are treated as elements of the same vague "set of all numbers," but in more rigorous contexts there is no such set (well, perhaps the complex numbers).
>>14381173
There are set theoretic definitions of real and complex numbers. For the reals, there are two main popular (equivalent) options, one of which is Dedekind cuts. The definition is sometimes referred to as a construction. I would sooner say it's "lower level" since it's more in the weeds, but it's a topic that's usually covered at the undergraduate level.

Anonymous

Anonymous Sun 10 Apr 2022 03:20:36 No.14381317 Report

Quoted By: >>14381324 >>14381327 >>14381336

>>14381101
$\mathbb{R} := \{x \in \mathbb{C} : \mathfrak{Im}(x) = 0\}$
$\mathbb{Q} := \left\{ \frac{x}{y} \in \mathbb{R} : \{ x \} = 0 \land \{ y \} = 0 \right\}$
$\mathbb{Z} := \left\{ x \in \mathbb{Q}: \{x\} = 0 \right\}$
$\mathbb{N} := \{x \in \mathbb{Z} : x \geq 0\}$
:)

Anonymous

Anonymous Sun 10 Apr 2022 03:26:52 No.14381324 Report

Quoted By: >>14381349

>>14381317
And how do you define the set of complex numbers?

Anonymous

Anonymous Sun 10 Apr 2022 03:28:01 No.14381327 Report

Quoted By:

>>14381317
>{x}=0
>{x}=0 and {y}=0

Anonymous

Anonymous Sun 10 Apr 2022 03:31:51 No.14381334 Report

Quoted By:

>>14381245
probably the same as an undergraduate in climate change, gene therapy or one of the memes of this decade. It would be the equivalent of an undergraduate in excel and spreadsheets in the 2000s

Anonymous

View Same Google iqdb SauceNAO a29f508196b8f5a82fd3f8dc2b551b5a.png, 1MiB, 1200x1080

Anonymous Sun 10 Apr 2022 03:32:18 No.14381336 Report

Quoted By:

>>14381317
Not formal enough. Read Jech.

Anonymous

Anonymous Sun 10 Apr 2022 03:39:59 No.14381349 Report

Quoted By:

>>14381324
They're constructed from elements of a weird set that no really cares about called the Dedekind set or the Cauchy set.

Anonymous

Anonymous Sun 10 Apr 2022 05:24:28 No.14381472 Report

Quoted By: >>14381496

>>14381254
tyvm anon, interesting stuff its definitely beyond me right now

what is the purpose or significance of something like the number 2 itself being called a set? is it something trivial that just happens to be so that more complex things make sense with this set theory?

Anonymous

Anonymous Sun 10 Apr 2022 05:48:34 No.14381496 Report

Quoted By:

>>14381472
Part of what makes math fun is finding the minimal number of assumptions you need to make to satisfy the things you want to be true. Following that, you can then do some research and learn other unexpected things that those assumptions imply.
So, some people got it in their head that it would be pretty neat if we could just assume the existence of a thing called a "set" and a couple of axioms about them, and then develop all of mathematics. Of course, one of the first things you'll want to use is numbers, so you develop the natural numbers first, and you develop it in such a way that you can ask what the "next" number is. Well, this is great, but now you want to define some operations on this set. This goes well until you try to subtract two natural numbers, so you develop another set of numbers called the integers (mirroring historical developments). Great: now you can subtract numbers from one another and talk about something called an "additive inverse." As has been the subject of some confusion here, you now have two "1"s: 1 in the natural numbers, and 1 in the integers. In order to justify loose discussion of "1" without reference to the specific element and set you're talking about, you might want a function mapping the natural numbers to the integers which preserves some of the properties you decide it ought to have. What's a function though? Well, that's another thing you can define with a set.
All of this is the content of the field of Set Theory.
That should answer how the concept of 2 as a set came about: for many, the purpose/significance is aesthetic simplicity and an ability to formulate complex looking mathematical statements in the basic (albeit lengthy) language of sets.

Capcode	All Only User Posts Only Moderator Posts Only Admin Posts Only Developer Posts
Show Posts	All Only With Images Only Without Images
Deleted Posts	All Only Deleted Posts Only Non-Deleted Posts
Ghost Posts	All Only Ghost Posts Only Non-Ghost Posts
Post Type	All Only Sticky Threads Only Opening Posts Only Reply Posts
Results	All Grouped By Threads
Order	Latest Posts First Oldest Posts First

Your latest searches