SOLUTION: Find the 7th term of the geometric sequence −8, 4, −2, ... (a) by listing out the first terms of the sequence. (b) by using a formula for finding the nth term of a ge

Algebra ->  Sequences-and-series -> SOLUTION: Find the 7th term of the geometric sequence −8, 4, −2, ... (a) by listing out the first terms of the sequence. (b) by using a formula for finding the nth term of a ge      Log On


   



Question 376960: Find the 7th term of the geometric sequence −8, 4, −2, ...
(a) by listing out the first terms of the sequence.
(b) by using a formula for finding the nth term of a geometric sequence.
Then a second one which is similar is finding the 10th term of the g.s. 3, 6, 12, ...
(a) by listing out the first 10 terms of the sequence.
(b) by using a formula for finding the nth term of a geometric sequence.

Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!

Hi,
geometric sequence -8, 4, -2,...
Finding the 7th term by listing out the first terms of the sequence:
-8, 4, -2, 1, -1/2, 1/4, -1/8, ...
using a formula for finding the nth term of a geometric sequence
a%5Bn%5D+=+a%5B1%5D%2Ar%5E%28n-1%29 where r is the common ratio. In this ex: r = (-1/2)
a%5Bn%5D+=+-8%2A%28-1%2F2%29%5E%28n-1%29
geometric sequence 3, 6, 12, ...
Finding the 10th term by listing out the first ten terms of the sequence:
3, 6, 12, 24, 48, 96, 192, 384, 768, 1536
using a formula for finding the nth term of a geometric sequence
a%5Bn%5D+=+a%5B1%5D%2Ar%5E%28n-1%29 where r is the common ratio. In this ex: r = 2
a%5Bn%5D+=+3%2A%282%29%5E%28n-1%29
CHECKING our Anwer
a%5B10%5D+=+3%2A%282%29%5E%289%29+=+1536