演習問題

${\displaystyle \left(\begin{array}{cc}1& 2\\ 3& 4\end{array}\right)+\left(\begin{array}{cc}5& 6\\ 7& 8\end{array}\right)}$

${\displaystyle \left(\begin{array}{c}\begin{array}{ccc}3& 7& 8\end{array}\\ \begin{array}{ccc}1& 5& 2\end{array}\end{array}\right)+\left(\begin{array}{c}\begin{array}{ccc}6& 2& 4\end{array}\\ \begin{array}{ccc}7& 1& 9\end{array}\end{array}\right)}$