Question

If $A=\left[\begin{array}{cc}2& 3\\ 1& 2\end{array}\right]$ and $B=\left[\begin{array}{ccc}1& 3& 2\\ 2& 3& 4\end{array}\right]$, then $AB$ equal to

• A. $\left[\begin{array}{ccc}8& 15& 16\\ 5& 9& 10\end{array}\right]$
• B. $\left[\begin{array}{cc}8& 5\\ 15& 9\\ 16& 10\end{array}\right]$
• C. $\left[\begin{array}{cc}8& 5\\ 15& 9\end{array}\right]$
• D. None of these

Answer 1

The correct option is A $\left[\begin{array}{ccc}8& 15& 16\\ 5& 9& 10\end{array}\right]$

$AB=\left[\begin{array}{cc}2& 3\\ 1& 2\end{array}\right]\left[\begin{array}{ccc}1& 3& 2\\ 2& 3& 4\end{array}\right]=\left[\begin{array}{ccc}2.1+2.2& 2.3+3.3& 2.2+3.4\\ 1.1+2.2& 1.3+2.3& 1.2+2.4\end{array}\right]=\left[\begin{array}{ccc}8& 15& 16\\ 5& 9& 10\end{array}\right]$
Ans: A