Question:
If $A$ and $B$ are 2 -rowed square matrices such that
$(A+B)=\left(\begin{array}{cc}4 & -3 \\ 1 & 6\end{array}\right)$ and $(A-B)=\left(\begin{array}{cc}-2 & -1 \\ 5 & 2\end{array}\right)$ then $A B=?$
A. $\left(\begin{array}{cc}-7 & 5 \\ 1 & -5\end{array}\right)$
B. $\left(\begin{array}{cc}7 & -5 \\ 1 & 5\end{array}\right)$
c. $\left(\begin{array}{rr}7 & -1 \\ 5 & -5\end{array}\right)$
D. $\left(\begin{array}{cc}7 & -1 \\ -5 & 5\end{array}\right)$
Solution:
$=\left(\begin{array}{cc}7 & -5 \\ 1 & 5\end{array}\right)$