0009.ptx

<exercise checkit-seed="0009" checkit-slug="M1" checkit-title="Multiplying matrices">
  <statement>
    <p>Of the following three matrices, only two may be multiplied.
      <me>
          A= \left[\begin{array}{ccc}
1 &amp; -1 &amp; -2 \\
3 &amp; -2 &amp; -3 \\
-5 &amp; 3 &amp; 5 \\
0 &amp; 2 &amp; 4
\end{array}\right]  \hspace{1em} B= \left[\begin{array}{ccc}
-1 &amp; -5 &amp; -2 \\
1 &amp; 4 &amp; 2
\end{array}\right]  \hspace{1em} C= \left[\begin{array}{cc}
-3 &amp; 4 \\
0 &amp; 1 \\
3 &amp; -1 \\
4 &amp; -6
\end{array}\right] </me>
      Explain which two can be multiplied and why. Then show how to find their product.</p>
  </statement>
  <answer>
    <me>CB= \left[\begin{array}{ccc}
7 &amp; 31 &amp; 14 \\
1 &amp; 4 &amp; 2 \\
-4 &amp; -19 &amp; -8 \\
-10 &amp; -44 &amp; -20
\end{array}\right] </me>
  </answer>
</exercise>