I got the answers $k = 4, 9$ for this problem: Find all real numbers $k$ for which there exists a nonzero, 2-dimensional vector ${v}$ such that
$\begin{pmatrix} 2 & 12 \\ 2 & -3 \end{pmatrix} {v} = k {v}$, but the way I obtained these answers seem a bit too easy. Is $k=4, 9$ correct?