SOLUTION: Find the sum of the infinite series: ∞ ∑ {{{ 4(1/5)^(k-1) }}} k=1

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Question 1177008: Find the sum of the infinite series:
∞
∑ +4%281%2F5%29%5E%28k-1%29+
k=1
Answer by ikleyn(52790) About Me  (Show Source):
You can put this solution on YOUR website!
.

Infinite geometric progression with the first term a = 4 and the common ratio r = 1%2F5.


Use the general formula for the sum


    Sum = a%2F%281-r%29 = 4%2F%281-1%2F5%29 = 4%2F%28%284%2F5%29%29 = 5.    ANSWER

Solved.