The geometric sequence is 
Explanation:
Given that the first term of the geometric sequence is 15
The fifth term of the sequence is 
We need to find the 2nd, 3rd and 4th term of the geometric sequence.
To find these terms, we need to know the common difference.
The common difference can be determined using the formula,

where
and
For
, we have,

Simplifying, we have,

Thus, the common difference is 
Now, we shall find the 2nd, 3rd and 4th terms by substituting
in the formula 
For 

Thus, the 2nd term of the sequence is 9
For
, we have,



Thus, the 3rd term of the sequence is 
For
, we have,



Thus, the 4th term of the sequence is 
Therefore, the geometric sequence is 