What is the sum of the first ten terms of the sequence - 82,-76,-70,-64?

To find the sum of a geometri sequence from first term to nth term you do

Sn = (n (a1+an)) / 2

a1=-82

n=10

hmm

common difference is 6 since adding 6 each time

first term is - 82

10th term is - 82+6 (10-1) = - 28

sum of 10 terms is

Sn = (10 (-82-28)) / 2

Sn = (10 (-110)) / 2

Sn = (-1100) / 2

Sn=-550

answer is - 550