Question

What is the sum of the geometric sequence -3, 18, -108,
if there are 8 terms?

Answer 1

Explanation:

using gp formula

tn=ar^n-1

which our a which is the first term is = -3

our r which is t2/t1=-6

t8=(-3)(-6)^8-1

=(-3)(-6)^7

=(-3)(-279936)

=839808