List of top Engineering Mathematics Questions on Eigenvalues and Eigenvectors asked in GATE TF

Two eigenvalues of the following matrix are 3 and 6. The third eigenvalue is \[ \begin{bmatrix} -2 & -4 & 2 \\ -2 & 1 & 2 \\ 4 & 2 & 5 \end{bmatrix} \]