Absolute Convergence Proof: The Relationship Between a_k and b_k

DEMJ
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Homework Statement



if a_k \le b_k for all k \in \mathbb{N} and \sum_{k=1}^{\infty} b_k is absolutely convergent, then \sum_{k=1}^{\infty} a_k converges.



Homework Equations


It's either true or false.


The Attempt at a Solution


I think a counterexample to prove it's false is if we let a_k=-1, b_k = 0 which satisfies a_k \le b_k and b_k is abs. convergent but \sum_{k=1}^{\infty} a_k diverges.
Is this a correct counterexample?
 
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that looks reasonable, if the ak & bk were positive numbers or it was written for maginutudes it would be true
 
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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