Linear Algebra - Eigenvalues

The sum of the eigenvalues of the matrix $A=\begin{bmatrix} 1 & 2 \\ 3 & 4 \end{bmatrix}^2$ is ________ (rounded off to the nearest integer).

M is a 2 x 2 matrix with eigenvalues 4 and 9. The eigenvalues of M² are

The eigenvalues of the matrix given below are $$\begin{bmatrix} 0 & 1 & 0 \\ 0 & 0 & 1 \\ 0 & -3 & -4 \end{bmatrix}$$