If possible, find AB, BA, and $A^2$. (If not possible, enter IMPOSSIBLE.)
$\begin{bmatrix} 2 & -2 \ -4 & 0 \ 9 & 6 \end{bmatrix}$, $B = \begin{bmatrix} 1 & 0 \ 0 & 1 \end{bmatrix}$
(a) AB
$AB = \begin{bmatrix} \boxed{} & \boxed{} \\ \boxed{} & \boxed{} \end{bmatrix}$
??
(b) BA
$BA = \begin{bmatrix} \boxed{} & \boxed{} \\ \boxed{} & \boxed{} \end{bmatrix}$
??
(c) $A^2$
$A^2 = \begin{bmatrix} \boxed{} & \boxed{} \\ \boxed{} & \boxed{} \end{bmatrix}$
