Question

Hi, can you please help me solve question number 9

Answer 1

`\begin{gathered} \begin{pmatrix}3 & 2 & -1\end{pmatrix}*\begin{pmatrix}5 & -1 & -1\end{pmatrix} \\ =\begin{pmatrix}2\mleft(-1\mright)-\mleft(-1\cdot\mleft(-1\mright)\mright) & -1\cdot\: 5-3\mleft(-1\mright) & 3\mleft(-1\mright)-2\cdot\: 5\end{pmatrix} \\ =\begin{pmatrix}-3 & -2 & -13\end{pmatrix} \end{gathered}`