## ridgeboy36 2 years ago What is the sum of the geometric sequence 2,8,32,... if there are 8 terms? Answers to choose from. a)21,845 b)43,690 c)65,535 d)87,380

1. geoffb

Do you know the formula for the sum of $$n$$ terms in a geometric sequence?

2. ridgeboy36

no could you guide me through this whole problem

3. geoffb

$\Large{S_{n} = \frac{a_{1}(1-r^{n})}{1-r}}$ $$a_{1}$$ is your first term. $$r$$ is the ratio (what you multiply by between each term). $$n$$ is the number of terms (given as 8).

4. ridgeboy36

ok

5. ridgeboy36

i got 43,690 as my answer is this correct?

6. geoffb

That's what I get.

7. ridgeboy36

thankyou

8. geoffb

No problem.