Using the graph below, what are the common ratio and the general term equation, an, of the geometric sequence?

Hint: an = a1(r)n − 1, where a1 is the first term and r is the common ratio

failurewithasmile
Apr 14, 2017

#1**+3 **

a_{1} = -24, a_{2} = -8, a_{3} = -8/3, ...

To go from a_{1} to a_{2}, divide by 3, or multiply by 1/3; thus the common ratio is 1/3.

To find a_{0}, multiply a_{1} by 3 (because you are going backwards) to get -72.

The formula for the n^{th} term is : a_{n} = a_{0}·r^{n} ---> a_{n} = 72 · (1/3)^{n}.

geno3141
Apr 14, 2017

#3**+1 **

Hi @CPhill, thanks for all of your help. I was wondering if the answer to this question is Is it r=1/3, an=-24(1/3)^n-1?

failurewithasmile
Apr 15, 2017