Question

Find the product of the matrices, if exists.

$(\begin{array}{cc}3& -2\\ 5& 1\end{array})(\begin{array}{cc}4& 1\\ 2& 7\end{array})$

Answer 1

$\left[\begin{array}{cc}3& -2\\ 5& 1\end{array}\right]\left[\begin{array}{cc}4& 1\\ 2& 7\end{array}\right]=\left[\begin{array}{cc}12-4& 3-14\\ 20+2& 5+7\end{array}\right]$

$=\left[\begin{array}{cc}8& -11\\ 22& 12\end{array}\right]$

Hence, the answer is $\left[\begin{array}{cc}8& -11\\ 22& 12\end{array}\right].$