Find the product of the matrices A and B where : $A=\begin{pmatrix}-5 & 1 & 3\\7 & 1 &-5\\1 & -1 & 1\end{pmatrix},B=\begin{pmatrix}1 & 1 & 2\\3 & 2 & 1\\2 & 1& 3 \end{pmatrix}$Hence,solve the following equations by matrix method:$x+y+2z=1,3x+2y+z=7,2x+y+3z=2.$
