Answer
$\begin{bmatrix} -2 & 5 & 0 \\ 6 & 6 & 5 \\ 12 & 2 & 5 \end{bmatrix} $
Work Step by Step
Consider $A=\begin{bmatrix} -1 & 2 & 0\\ 0&3&2\\0 &1&4 \end{bmatrix} $ and $B=\begin{bmatrix} 2 & -1 & 2 \\ 0 & 2 & 1\\ 3& 0& -1\end{bmatrix} $
Since, the dimensions of both matrix $A$ and $B$ is $3 \times 3$ .This follows that the number of columns of matrix-$A$ will be same as the number of rows of the matrix-$B$ and so, we can take their product $AB$.
$AB=\begin{bmatrix} -1 & 2 & 0\\ 0&3&2\\0 &1&4 \end{bmatrix} \begin{bmatrix} 2 & -1 & 2 \\ 0 & 2 & 1\\ 3& 0& -1\end{bmatrix}\\=\begin{bmatrix} -2&1+4& -2+2+0 \\ 0+0+6 & 0+6+0 &0+3+2\\0+0+12&0+2+0&0+1+4 \end{bmatrix}$
$ \\ =\begin{bmatrix} -2 & 5 & 0 \\ 6 & 6 & 5 \\ 12 & 2 & 5 \end{bmatrix} $
