Number Theory- arithmetic functions

roca
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Problem: Show that for each k, the function σk(n)=Ʃd|n dk is multiplicative.



The attempt at a solution:

What I know is that I am supposed to use the Lemma which states that if g is a multiplicative function and f(n)=Ʃd|n g(d) for all n, then f is multiplicative. I am just very confused on how to apply this theorem to my problem.
 
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What would g be in this case?
 
just a function
 

Thread 'Finding the nth roots of a complex number'

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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