Question

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.

Answer 1

Given that the geometric series is given by:
an=a1(r)^(n-1)
where:
a1= first term
r=common ratio
n=number of terms:
from the graph, our sequence is:
-32,-24,-18,...
where:
a1=-32
a2=-24
a3=-18
thus
common ratio, r=-24/-32=3/4

thus the general form will be:
an=-32(3/4)^(n-1)