What is the Induction Process for Finding det(alpha*A)?

DMOC
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Old topic: https://www.physicsforums.com/showthread.php?t=194725

I have a question that's the same as the one in the old topic/thread I linked to above. At the last post, I am trying to figure out how to carry out the induction process.

\sum_{j=1}^n (-1)^{i+j} a_{ij} det(\alpha A_{ij})

I understand that all det(\alpha A_{ij}) will be k x k matrices because they are basically (k+1)x(k+1) matrices but without the ij row/column so those matrices will fall under the range of induction, i.e. between 2 and k, inclusive.

But if I substitute det(\alpha A_{ij}) with \alpha^n det(A_{ij}) I will get \sum_{j=1}^n (-1)^{i+j} a_{ij} \alpha^ndet(A_{ij})

Where do I get the extra n so that it becomes alpha ^ n + 1. (Note: when I write out the actual proof, I'll use alpha^(k+1) instead of n + 1)?
 
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a_ij is supposed to be the ijth element of the matrix alpha*A, not A. You are trying to find det(alpha*A). It should be alpha*a_ij.
 
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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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