Question

What is the sum of the arithmetic sequence 6, 14, 22 …, if there are 26 terms?

Answer 1

This is an arithmetic sequence. First of all determine the 26th term. Do you have any idea of what formula you should use?

Answer 2

do you use: Sn=n/2 [2a[1]+(n-1)d]?

Answer 3

Yeah. I use this formula:

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

Though you really don't need to. So first determine the 26th term.

\( \color{Black}{\Rightarrow \Large a_{26} = 6 + [(25)\times 8] }\)

Answer 4

206

Answer 5

Now plug it in, into the sum formula.

\( \color{Black}{\Rightarrow \Large {26 \over 2}(6 + 206)}\)

Answer 6

2756

Answer 7

thank you!

Answer 8

Correct :)

Answer 9

yw =) =)