Question

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

2,754

2,756

2,758

2,760

Answer 1

the common difference d = 8 n = 26 and a = 6

then \[s _{n} = \frac{n}{2}(2a + (n -1) d)\]

substitute into the formula and evaluate...

it may help to remember the formula.

Answer 2

First, find the 26th term.

\(\Large \color{MidnightBlue}{\Rightarrow a_{n} = a_{1} + (n - 1)d }\)

Then, see what the sum is.

\(\Large \color{MidnightBlue}{\Rightarrow S_{n} = {n \over 2}(a_{1} + a_{l}) }\)
a1 = first term
aL = last term

Answer 3

checkout the attachment