Identify the elementary matrices or neither (write your answer below the matrices) a) $\left(\begin{array}{cc) & -3 1 0 & 1\end{array} ight) b) $\left(\begin{array}{111}1 & 0&111 & 1 & 10 & I\end{array} ight) c) $\left(\begin{array{ccc}l & & 0 -1 / 2 & 1 & 0 1 0 & 0 & 1\end{array} ight)$ d) $\left(\begin{array}{ccc}i & 9 & 15 1 1 & 0& 9 10 & 9 & 1\end{array} ight) e) $\left(\begin{array}{ccc}1 & 0&&1&O 10 & 0& -2 / 3\end{array} ight)$ If $A=\left(\begin{array}{ccc}l & -1 & 1 2 & -2 & 3 4 & 5 & 2\end{array} ight) and $B=\left(\begin{array}{cc) 3& -1 11 1&1 3 & alend{array} ight) and $C=A B$. Find the value $a$ so that the element $c_{22]$ of the matrix $\mathrm{C}$ equals 8 - SP.SD. 344