<exercise checkit-seed="0008" checkit-slug="M1" checkit-title="Multiplying matrices">
<statement>
<p>Of the following three matrices, only two may be multiplied.
<me>
A= \left[\begin{array}{cccc}
1 & -3 & 3 & 2 \\
2 & -5 & 6 & 1 \\
0 & 0 & 1 & -2
\end{array}\right] \hspace{1em} B= \left[\begin{array}{ccc}
-1 & -3 & -1 \\
2 & 5 & 2
\end{array}\right] \hspace{1em} C= \left[\begin{array}{cccc}
1 & 3 & 1 & 5 \\
0 & 0 & 1 & 1
\end{array}\right] </me>
Explain which two can be multiplied and why. Then show how to find their product.</p>
</statement>
<answer>
<me>BA= \left[\begin{array}{cccc}
-7 & 18 & -22 & -3 \\
12 & -31 & 38 & 5
\end{array}\right] </me>
</answer>
</exercise>