(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

This is a question taken from an old exam so I am not sure to which subject in calculus it's connected to...

Prove the inequality:

[itex]\frac{1}{4(ln2)^2}[/itex][itex]\leq[/itex][itex]\sum\frac{2^n}{2^(2^n)}[/itex]

(sigma is from 1 to +inf, and the Denominator on the right side is (2^(2^n))

2. Relevant equations

3. The attempt at a solution

Well, I solved it by calculating the first 3 elements of the sum showing their sum is larger than the left side, and that proves it. But, I don't think that's the way I suppose to solve it!

(I thought it somehow connected to derivative of the sum of the integrals of the function in the sigma.

Any help would be greatly appreciated.

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# Prove the inequality - 1\4(ln2)^2 <= sigma(2^n\(2^(2^n)))

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