What test should be used to determine the convergence of this series?

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Homework Statement



http://i.imgur.com/1a1aT.png

Homework Equations



comparison test
alternating series test

The Attempt at a Solution



I know the limit of this is zero and it's decreasing so it's either conditionally or absolutely convergent, but I do not know what test to use so I can be sure. I tried comparing it to 1/[(n^3)+1] but its less than the series and convergent meaning the comparison test doesn't work. I tried the limit comparison test and get infinity meaning it doesn't work. What is the right way to find of this problem is absolutely or conditionally convergent?
 
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Alternating series test.
 
Also, it looks close to 1/n^(1.5) for sufficiently large n. That might be a good comparison.
 
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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