Answer :
[tex]\lambda[/tex] is an eigenvalue of a matrix [tex]\mathbf A[/tex] if for some non-zero vector [tex]\mathbf x[/tex], you have
[tex]\mathbf{Ax}=\lambda\mathbf x[/tex]
where [tex]\mathbf x[/tex] is the associated eigenvector.
[tex]\mathbf{Ax}=\lambda\mathbf x[/tex]
where [tex]\mathbf x[/tex] is the associated eigenvector.