I have a problem in my homework in which I have to find the characteristic polynomial of the following matrix:
I know the final solution is:
However, my answer keeps getting wrong whenever I calculate with the following way: I know that I have to find the determinant of: (λI-A), but I decided to use some Gauss methods to simplify the matrix, so I won't get a x^3 in my final polynomial.
Therefore, I did the following actions:
Please help me get what I did wrong, and this would be a great help for me.
Thank you,
Alan