Resposta :
[tex]\left(
\begin{array}{cccc}
{1 & 2 & 3}\\
3 & 1 & 2}\\
\end{array} \right ) \cdot \left(
\begin{array}{cccc}
{2 & 1}\\
3 & 2}\\
4 & 5}
\end{array} \right )=\left(
\begin{array}{cccc}
{20 & 20}\\
17 & 15}\\
\end{array} \right )[/tex]