Determining Convergence/Divergence Of Infinite Series

Bashyboy
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Homework Statement


I attached the solution to the problem.


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The Attempt at a Solution


I can see that the infinite series diverges by looking at a few terms, but how would I find a general term for the infinite series, to evaluate it analytically?
 

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Bashyboy said:
I can see that the infinite series diverges by looking at a few terms, but how would I find a general term for the infinite series, to evaluate it analytically?

If your goal is to prove that the series diverges, you don't necessarily need to find an expression for the general term (by which I assume you mean the n'th partial sum).

There is a very simple test which you should always apply as the first step. If this test fails, the series diverges. What test am I referring to?
 
Would it be the nth term test?
 
Yes. What does that test imply for this series?
 
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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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