Rank of a Matrix: Determine Value of k

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Homework Statement



Determine the values of k, if any, that give the matrix (1,1,k),(1,k,1),(k,1,1) a rank of: zero, one, two, or three.

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The Attempt at a Solution



I tried reducing to row echelon form but it's confusing dealing with all the k's. Is there a better approach to this?
 
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The row echelon form of this matrix is not very complicated, however it depends on the value of k. So whenever you divide by some value involving k while computing it, you will need to consider special cases (k=1, k=-2).
 
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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