Question

Find the sum of the first 9 terms of the sequence. Show all work for full credit.

2, -7, -16, -25, ...

Answer 1

this is an arithmetic series with common difference -9

Answer 2

im really confused on how to solve it

Answer 3

Sn = (n/2)[2a1 + (n -1)d]

where a1 = first rems, n = number of terms and d = common difference

Answer 4

Sn is sum of n terms , here n = 9

Answer 5

just plug the values into the formula

Answer 6

oh ok thanks. i understand

Answer 7

yw

Answer 8

your answer is approximately -300