Proving Invertible Matrix Property: kth Power

ephemeral1
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Homework Statement



Prove: If A is an invertible matrix and k is a positive integer, then
(A^k)^-1 = (A^-1)(A^-1) ...A^-1=(A^-1)^k

Homework Equations


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The Attempt at a Solution



I have a hard time proving this. How do I go about doing this? Any help would be great. I really want to understand this. Thank you.
 
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Just multiply A^k by (A^{-1})^k and show you get the identity matrix.
 
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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