Question

What is the 41st term of the arithmetic sequence where a1 = 17 and a15 = –39 ?

Answer 1

`-143`

Explanation:

`a_n = a_1 + (n - 1) r`

`a_15 = a_1 + 14 r`

`-39 = 17 + 14 r`

`-56 = 14 r`

`-4 = r`

`a_41 = a_1 + 40 r = 17 - 4 * 40`