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Anonymous Tue 29 Sep 01:55:24 2020 No.12173324 View Reply Original Report

Quoted By: >>12173707

In an arithmetic sequence, the 19th term is seven times the second term and the eight term is 53. Find A, the first term and D the distance between terms.

This one has me stumped guys someone please help please

Anonymous

Anonymous Tue 29 Sep 2020 01:58:03 No.12173332 Report

Quoted By: >>12173378

Anonymous

Anonymous Tue 29 Sep 2020 02:12:15 No.12173378 Report

Quoted By:

>>12173332
Wrong

Anonymous

Anonymous Tue 29 Sep 2020 02:21:45 No.12173399 Report

Quoted By: >>12173692

A=11
D=6

Anonymous

Anonymous Tue 29 Sep 2020 05:20:28 No.12173692 Report

Quoted By: >>12174380

>>12173399
Worked it out (not OP,) this is the correct answer.
Very simple: just make 2 equations from the data given. The first one: 19th term = 7* 7th term. Let the 19th term be a + 18d (d = common difference, a = first term) and the 7th term be a + 7d. We get 6a = 11d. Then, since the 8th term (a + 7d) is 53, we can just substitute one of a or d for the other using 6a = 11d to solve.

Anonymous

Anonymous Tue 29 Sep 2020 05:27:35 No.12173707 Report

Quoted By:

>>12173324
an = A + (n-1)D by definition
A+7D = 53
A+18D = 7(A+n)
solve for A, D

Anonymous

Anonymous Tue 29 Sep 2020 12:09:13 No.12174380 Report

Quoted By:

>>12173692
Why does 6a equal 11d?

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