Answer
$8$
Work Step by Step
If A is an $\mathrm{m}\times\fbox{$\mathrm{p}$}$ matrix, and B is a $\fbox{$\mathrm{p}$}\times \mathrm{n}$ matrix,
the product AB is defined, and is an $\mathrm{m}\times \mathrm{n}$ matrix.
The element $c_{ij}$ of the product matrix $C=AB$ is found as follows.
$c_{ij}=a_{i1}b_{1j}+a_{i2}b_{2j}+\cdots+a_{in}b_{nj}$
$x=c_{11}=2\times 3+1\times 2=8$
