What is the sum of an 8-term geometric series if the first term is - 11, the last term is 859,375, and the common ratio is - 5?

-143,231

716,144

144,177

-36,047

... ?

A geometric sequence is when numbers in sequence have a common ratio. To solve this problem, we need the equation for the sum of a geometric sequence.

Sum = (a1 (1-r^n)) / (1-r)

We do as follows:

Sum = (-11 (1 - (-5) ^8)) / (1 - (-5))

Sum = - 1074216