Question

In an arithmetic sequence, the sum of the first n terms is s_n=n^2. find a_8

i'm not sure how to do this, so yeah

Answer 1

`a_(8) = 15`

Explanation:

`a_(1) + a_(2) + ..... + a_(7) + a_(8) = 8^(2) = 64`

`-a_(1) - a_(2) ..... - a_(7) = - 7^(2) = -49` Now add the two equations

`a_(8) = 64 - 49 = 15`

`a_(8) = 15`