What is the sum of a 7-term geometric series if the first term is −11, the last term is −171,875, and the common ratio is −5?

−143231

The general term of a geometric series can be described by the formula:

an=arn−1

where the initial term is a and common ratio r.

Then we find:

So dividing both ends by (1−r) we find:

N∑n=1an=a(1−rN)1−r

In our example, N=7, a=−11 and r=−5

So:

0.85 or 85%

step-by-step explanation:

1) divide 23 by 27

2) round the decimal to the nearest 10

3) so your answer would be 0.85 or 85%

the answers are in the images, i received 100% on this assignment. hope this !