Question

What is the sum of a 30-term arithmetic sequence where the first term is 74 and the last term is -100?

Answer 1

\( \color{Black}{\Rightarrow \Large {n \over 2}({a_1 + a_n)} }\)

Does that help?

Answer 2

what do i plug in to that?

Answer 3

Plug n with 30.

Answer 4

a30 would obviously be the last term.

Answer 5

\( \color{Black}{\Rightarrow \Large a_n = a_{last} }\)

Answer 6

then leave a1 as a1

Answer 7

a1 is the first term.
an is the last term.
n is the number of terms.