## anonymous one year ago Find the sum of an 8-term geometric sequence when the first term is 7 and the last term is 114,688 and select the correct answer below. 152,915 16,384 16,377 152,908

1. anonymous

@superhelp101 @welshfella @paki @butterflydreamer @ganeshie8

2. anonymous

you are given a you are given Sn the sum of the terms do you know the formula for the sum of the terms?

3. anonymous

Sn = a1 - a1rn/ 1 - r

4. anonymous

what you are not given is r, the common ratio.

5. anonymous

Are you sure you weren't given a common ratio, r, in the question?

6. freckles

$a,ar,ar^2,ar^3,...,ar^7 \\ \\ \text{ you are given } ar^7=114688 \text{ and } a=7 \\ \text{ so you can find } r \\ \text{ just solve } 7r^7=114688 \text{ for } r$