Problem: In a geometric series of positive terms the difference between the fifth and fourth terms is , and the difference between the second and first terms is . What is the sum of the first five terms of this series?
Answer Choices:
A.
B.
C.
D.
E. none of these
Solution:
The sum of the first five terms of the geometric series with initial term a and common ratio is
By hypothests and . Dividing the last equation into the first yields so and . Since and and therefore .