Question

Hi guys, I am struggling with finding the characteristic polynomial and eigenvalues of a 3x3 matrix in a change of coordinates problem. Basically, I have to take the equation x^2 - z^2 - 4xy +4yz and convert it into a matrix and find the eigenvalues. I converted the quadratic form into the following symmetric matrix A: [1 -2 0; -2 0 2; 0 2 1] In order to get the eigenvalues, I must find the det(A-(lambda)I)=0, but using the cofactor expansion rule and subsequently expanding and factoring, I cannot find the polynomial nor factor it in order to the (lambda) values that satisfy the equat

Answer 1

wat is ur det(A-(lambda))