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algebra senior
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?
(A)
(B)
(C)
(D)
Solution
Let the first term be and the common ratio be . Therefore, the second term is , the fourth term is , and the fifth term is . We're given that and . Dividing this first equation by this second one, we get . Therefore, , so . Therefore, the first five terms of this series are , and their sum is .
Final answer
B