Question

What is an eigenvalue?

Answer 1

If `A` is any `nxxn` square matrix, then the eigenvalues of A are those values `lambda` for which the determinant `det(A-lambdaI)=0`, (the zero matrix), where `I` is the `nxxn` identity matrix.

The corresponding vectors `x` such that `Ax=lambdax` are called the eigenvectors corresponding to the eigenvalues `lambda`.