SOLUTION: find the common difference, the first term, and the recursive formula for the nth term. Given a3=14 and a8=-3.5

Algebra ->  Sequences-and-series -> SOLUTION: find the common difference, the first term, and the recursive formula for the nth term. Given a3=14 and a8=-3.5      Log On


   

Question 860718: find the common difference, the first term, and the recursive formula for the nth term. Given a3=14 and a8=-3.5
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi,

a%5B3%5D+=+a%5B1%5D+%2B+2d+=+14

a%5B8%5D+=+a%5B1%5D+%2B+7d++=+-3.5

           -5d = 17.5    |subtracting a8 from a3

            d = -3.5   and a%5B1%5D+=+21%0D%0A%7B%7B%7Ba%5Bn%5D+=+21+%2B+%28n-1%29%28-3.5%29

a%5Bn%5D+=+-3.5n+%2B+24.5+%29

CHECKING our answer***

a%5B8%5D+=+-28+%2B+24.5+=+-3.5

Wish You the Best in your Studies.