/sci/ - Science & Math » Thread #11343170

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are mathbook wrritten by women a mistake?

Anonymous Wed 29 Jan 19:37:11 2020 No.11343170 View Reply Original Report

Quoted By: >>11343195 >>11343197 >>11343207 >>11343319 >>11343447 >>11343462 >>11343497 >>11343573 >>11343741 >>11344386 >>11344684 >>11344694 >>11344710

I picked up this Mcgraw Hill book to study algerabra. Overall it's a decent book really. But there are either outright contradictions or unclear teaching in it. What does /sci/ think about this? Bad writing or i'm reading it wrong?

Anonymous

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Anonymous Wed 29 Jan 2020 19:37:49 No.11343172 Report

Quoted By: >>11343195 >>11343197 >>11343207 >>11343225 >>11343447 >>11343462 >>11343573 >>11344684 >>11344694

Anonymous

Anonymous Wed 29 Jan 2020 19:42:47 No.11343190 Report

Quoted By:

I can't read. What are you unclear about?

Anonymous

Anonymous Wed 29 Jan 2020 19:43:37 No.11343195 Report

Quoted By:

>>11343170
>>11343172
Fuck off you worthless ESL there's nothing wrong with either of these images.

Anonymous

Anonymous Wed 29 Jan 2020 19:44:22 No.11343197 Report

Quoted By: >>11343219

>>11343170
>>11343172
I don't see an issue with it. What are you trying to say here?

Anonymous

Anonymous Wed 29 Jan 2020 19:47:57 No.11343207 Report

Quoted By:

>>11343170
>>11343172
The only "problem" I can find is that they don't define what "distance" means but given that this is what looks to be an elementary school textbook, that seems fine.

Anonymous

Anonymous Wed 29 Jan 2020 19:51:28 No.11343219 Report

Quoted By: >>11343224 >>11343447

>>11343197
>absolute value is always non negative
[-5=5]
>definition of the absolute value of a real number
>if a is negative (<0) [a=-a]
Is it a contradiction? It might just be the way my brain works. And i'm not a math whiz so i'm having a hard time explaining it. I think they're defining real numbers and not absolute value in the second case? Idk.

Anonymous

Anonymous Wed 29 Jan 2020 19:53:31 No.11343224 Report

Quoted By: >>11343236

>>11343219
-(-7)=7

Anonymous

Anonymous Wed 29 Jan 2020 19:53:36 No.11343225 Report

Quoted By:

>>11343172
If a is negative, for instance -7, then the absolute number is -a, meaning -(-7)=7

Anonymous

Anonymous Wed 29 Jan 2020 19:56:58 No.11343236 Report

Quoted By: >>11343253 >>11343265 >>11343273 >>11343798

>>11343224
I know that. I'm just starting at the beginning of the book. I'm just hung up on them saying absolute value is non negative then they show one being negative on the next page. I guess it doesn't say always.

Anonymous

Anonymous Wed 29 Jan 2020 20:01:30 No.11343253 Report

Quoted By:

>>11343236
all the book shows is that the thing inside the double bars on the left side of the equals sign will never simplify into a real constant with a minus sign on the right side of the equals sign. There's no contradiction here.

Anonymous

Anonymous Wed 29 Jan 2020 20:04:19 No.11343265 Report

Quoted By:

>>11343236
Think of the absolute value as a function, abs(x).
He's saying abs(x) is never negative, even if x is negative. That means that if x is negative, abs(x) = -x, since -(-x) = +x.

Anonymous

Anonymous Wed 29 Jan 2020 20:06:08 No.11343273 Report

Quoted By: >>11343301 >>11343335

>>11343236
it's just giving a more rigorous definition of absolute value, which is multiplying negative numbers by -1 (in the text explained as "opposite") and positive numbers by 1 (no-operation).

Anonymous

Anonymous Wed 29 Jan 2020 20:16:38 No.11343301 Report

Quoted By:

>>11343273
Hmmm. Ok.

Anonymous

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Anonymous Wed 29 Jan 2020 20:23:27 No.11343319 Report

Quoted By: >>11343344 >>11343345 >>11343467

>>11343170
>look at the number. Now, cover up the sign with your left thumb. That's the absolute value.

Anonymous

Anonymous Wed 29 Jan 2020 20:31:31 No.11343335 Report

Quoted By:

>>11343273
absolute value is a distance function to 0 which is using the pithagorean theorem and only count the positive: d = +sqrt(x^2 + y^2)

Anonymous

Anonymous Wed 29 Jan 2020 20:35:09 No.11343344 Report

Quoted By:

>>11343319
Yhea, i know, i just get distracted easily and forget the big picture, thank man.

Anonymous

Anonymous Wed 29 Jan 2020 20:35:19 No.11343345 Report

Quoted By: >>11343560

>>11343319
ahhahaha, they teach this everywhere?

Anonymous

Anonymous Wed 29 Jan 2020 21:20:11 No.11343447 Report

Quoted By: >>11343466 >>11343471

>>11343170
>>11343172
I see aboslutely no problem with this.
>>11343219
>>if a is negative (<0) [a=-a]
>Is it a contradiction?
Yes, that is a contradiction, but that's not what the book is saying. You seem to be confusing absolute value notation with square brackets. Do you see the difference here?
$|x| \neq [ x ]$

Those enclosing symbols on the left isn't reglar square brackets, it is notation for the absolute value function. Can you see how they are different? The defition of this absolute value function is

$ |a| = \begin{cases} a& \text{ if }\, a \geq 0 \\ -a& \text{ if }\, a < 0 \\ \end{cases} $

Anonymous

Anonymous Wed 29 Jan 2020 21:25:20 No.11343462 Report

Quoted By:

>>11343172
>>11343170
Actual low IQ detected.

Anonymous

Anonymous Wed 29 Jan 2020 21:27:32 No.11343466 Report

Quoted By:

>>11343447
Yes i see. I only used those symbols because reasons. Don't have absolute value notation on this device.

Anonymous

Anonymous Wed 29 Jan 2020 21:27:39 No.11343467 Report

Quoted By: >>11343479

>>11343319
What if I lost my left thumb in a freak gardening accident?

Anonymous

Anonymous Wed 29 Jan 2020 21:28:50 No.11343471 Report

Quoted By:

>>11343447
Also that notation at the bottom is way better than the book does it.

Anonymous

Anonymous Wed 29 Jan 2020 21:32:05 No.11343479 Report

Quoted By:

>>11343467
Then math may not be for you, sorry.

Anonymous

Anonymous Wed 29 Jan 2020 21:39:08 No.11343497 Report

Quoted By:

>>11343170
>MGH

Anonymous

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Anonymous Wed 29 Jan 2020 21:58:44 No.11343560 Report

Quoted By:

>>11343345
Obviously.

Anonymous

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Anonymous Wed 29 Jan 2020 22:02:58 No.11343573 Report

Quoted By: >>11343863

>>11343170
>>11343172
goddamn OP you really are a fucking retard. why do I visit this board

Anonymous

Anonymous Wed 29 Jan 2020 22:56:40 No.11343741 Report

Quoted By: >>11343743

>>11343170
Is 0 nonnegative?

Anonymous

Anonymous Wed 29 Jan 2020 22:57:59 No.11343743 Report

Quoted By: >>11343806

>>11343741
yes

Anonymous

Anonymous Wed 29 Jan 2020 23:15:51 No.11343798 Report

Quoted By:

>>11343236
the absolute value is non negative.

It can be expressed of the negative of a negative.

Anonymous

Anonymous Wed 29 Jan 2020 23:22:18 No.11343806 Report

Quoted By: >>11343809

>>11343743
That means -0 != +0.

Anonymous

Anonymous Wed 29 Jan 2020 23:24:23 No.11343809 Report

Quoted By: >>11343821

>>11343806
What the fuck are you talking about
-0=0=+0
0 isnt negative or positive. It is non-negative.

Anonymous

Anonymous Wed 29 Jan 2020 23:32:14 No.11343821 Report

Quoted By: >>11343834

>>11343809
https://math.stackexchange.com/questions/26705/is-zero-positive-or-negative

Anonymous

Anonymous Wed 29 Jan 2020 23:40:44 No.11343834 Report

Quoted By: >>11343862

>>11343821
>zero is unsigned, that is, it is neither positive nor negative
Damn, I guess I was right after all. Are you OP?

Anonymous

Anonymous Wed 29 Jan 2020 23:56:38 No.11343862 Report

Quoted By: >>11343864

>>11343834
>cherrypicking
It's a matter of context.

Anonymous

Anonymous Wed 29 Jan 2020 23:58:41 No.11343863 Report

Quoted By:

>>11343573
You could just ignore bad threads like the rest of us do.

Anonymous

Anonymous Wed 29 Jan 2020 23:59:04 No.11343864 Report

Quoted By: >>11343867

>>11343862
You should be very embarrassed if you are OP.

Anonymous

Anonymous Thu 30 Jan 2020 00:00:32 No.11343867 Report

Quoted By:

>>11343864
>still replying
I'm not OP. I just wanted to nitpick that 0 isn't nonnegative in any context.

Anonymous

Anonymous Thu 30 Jan 2020 03:11:28 No.11344386 Report

Quoted By: >>11344387

>>11343170
>nonnegative
like... positive integers?

Anonymous

Anonymous Thu 30 Jan 2020 03:12:09 No.11344387 Report

Quoted By: >>11344397

>>11344386
All positive numbers and zero

Anonymous

Anonymous Thu 30 Jan 2020 03:15:56 No.11344397 Report

Quoted By: >>11344486

>>11344387
Ok so why write "nonnegative" when exist better and more precise words

Anonymous

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Anonymous Thu 30 Jan 2020 03:26:32 No.11344424 Report

Quoted By:

op really wanted to las out at women today, huh?

Anonymous

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Anonymous Thu 30 Jan 2020 03:33:55 No.11344428 Report

Quoted By: >>11344435

this is fucking horrific, they got paid for this?

Anonymous

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Anonymous Thu 30 Jan 2020 03:38:18 No.11344435 Report

Quoted By: >>11344462

>>11344428
it is easy to get tilted by informal stuff until you realize life is too short to belittle people who learn better through engaging texts and have fun or stay interested doing so
I mean as long as they do not go on to watch vsauce because "herp I learned more these 10 minutes than I did in all of school"

Anonymous

Anonymous Thu 30 Jan 2020 03:53:35 No.11344462 Report

Quoted By:

>>11344435
>chemicals surge
absolutely fucking based and chad

Anonymous

Anonymous Thu 30 Jan 2020 04:04:23 No.11344486 Report

Quoted By:

>>11344397
Like what?..

Anonymous

Anonymous Thu 30 Jan 2020 06:22:59 No.11344684 Report

Quoted By:

>>11343170
>>11343172
I can see where the confusion might stem from. Its probably not inherent or intuitive to retards, but i believe in you OP. Just try your best! :)

Anonymous

Anonymous Thu 30 Jan 2020 06:34:03 No.11344694 Report

Quoted By:

>>11343170
>>11343172
You're actually retarded. I'm sorry anon

Anonymous

Anonymous Thu 30 Jan 2020 06:45:11 No.11344710 Report

Quoted By:

>>11343170
Why must I share a board with people like you, OP? Please leave and never come back.

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