Written Assignment
1. Let
$\begin{aligned}
A &= \begin{bmatrix} 2 & 0 & -1 \\ 4 & -5 & 2 \end{bmatrix}, \\ B &= \begin{bmatrix} 7 & -5 & 1 \\ 1 & -4 & -3 \end{bmatrix}, \\ C &= \begin{bmatrix} 1 & 2 \\ -2 & 1 \end{bmatrix}, \\
\end{aligned}$
and
$\begin{aligned}
D &= \begin{bmatrix} 3 & 5 \\ -1 & 4 \end{bmatrix}, \\ x &= \begin{bmatrix} -5 \\ 3 \end{bmatrix}.
\end{aligned}$
Either compute the following expressions or give the reason why they are undefined:
a.) $B - \frac{1}{2}A$
b.) $AC$
c.) $CD$
d.) $A + 3B$
