How to prove Convergence of this Series

Euler2718
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Homework Statement



Use any appropriate test to determine the convergence or divergence of the following series:

\sum_{i=0}^{\infty} \frac{2^{i} + 3^{i}}{4^{i}+5^{i}}

Homework Equations

The Attempt at a Solution



I've run it through mathematica and it told me it's convergent. However, I can't seem to find the right test to use. Ratio test / Limit comparison doesn't seem to work as nothing cancels, I can't find a test series for direct comparison, and root test wouldn't work? Have I over looked anything?
 
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You can start with an asymptotic approach ##\sum_{i=0}^{\infty}\frac{2^{i}+3^{i}}{4^{i}+5^{i}}\sim \sum_{i=0}^{\infty}\frac{3^{i}}{5^{i}}##
 
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Morgan Chafe said:

Homework Statement



Use any appropriate test to determine the convergence or divergence of the following series:

\sum_{i=0}^{\infty} \frac{2^{i} + 3^{i}}{4^{i}+5^{i}}

Homework Equations

The Attempt at a Solution



I've run it through mathematica and it told me it's convergent. However, I can't seem to find the right test to use. Ratio test / Limit comparison doesn't seem to work as nothing cancels, I can't find a test series for direct comparison, and root test wouldn't work? Have I over looked anything?
Try comparison test.
Hint: if 0<a<b and 0<c, 0<d, then ##\frac{a+b}{c+d}\leq \frac{2b}{d}##
 
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How about : ## 0<a<b<c<d ## then ##\frac {a+b}{c+d} ##?
 
Ssnow said:
You can start with an asymptotic approach ##\sum_{i=0}^{\infty}\frac{2^{i}+3^{i}}{4^{i}+5^{i}}\sim \sum_{i=0}^{\infty}\frac{3^{i}}{5^{i}}##
Samy_A said:
Try comparison test.
Hint: if 0<a<b and 0<c, 0<d, then ##\frac{a+b}{c+d}\leq \frac{2b}{d}##

Alright I think I got it now, thanks.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...

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