Find Eigenvectors of 3x3 Matrix

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Homework Statement


Find the eigenvalues and an orthonormal set of eigenvectors for this matrix:

|1 1+i 0|
|1-i 1 0|
|0 0 2|

Homework Equations


Find the determinant of A - xI, where A is the matrix, I is the identity matrix, and x denotes eigenvalues
Set the determinant equal to 0, and then find eigenvectors for each eigenvalue


The Attempt at a Solution



If x denotes an eigenvalue, I found the determinant of this matrix to be (2-x)((1-x)(1-x) - (1+i)(1-i)) = (2-x)(x^2 - 2x - 1). Then I got stuck, since I do not know how to factor this equation. How do I find the eigenvalues for this matrix? Am I doing something wrong?
 
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You've already factored it as much as you need to. What's left is a quadratic equation. You can solve that without factoring, can't you?
 
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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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