Question

What is the sum of a 17-term arithmetic sequence where the first term is 6 and the last term is -90?

A. -813
B. -790
C. -765
D. -714

Answer 1

\( \color{Black}{\Rightarrow S = \large {n \over 2}(a_1 + a_{last}) }\)

Answer 2

I don't understand where to plug in which numbers

Answer 3

\(n\) is the number of terms, here 17.
\(a_1\) is the first term, here 6.
\(a_{last}\) is the last term, here -90.

Answer 4

so after plugging all the numbers in, would S be the answer?

Answer 5

Yes :D

Answer 6

okay thank you so much!

Answer 7

The answers aren't matching...