Question

If $A=\left[\begin{array}{ccc}1& 2& 3\\ 3& 2& 1\end{array}\right]$ and $B=\left[\begin{array}{ccc}3& 2& 1\\ 1& 2& 3\end{array}\right]$, find $3B-2A$.

Answer 1

We have, $A=\left[\begin{array}{ccc}1& 2& 3\\ 3& 2& 1\end{array}\right]$ and $B=\left[\begin{array}{ccc}3& 2& 1\\ 1& 2& 3\end{array}\right]$

So $2A=\left[\begin{array}{ccc}2& 4& 6\\ 6& 4& 2\end{array}\right]$ and $3B=\left[\begin{array}{ccc}9& 6& 3\\ 3& 6& 9\end{array}\right]$

( multiply all the elements )

$\therefore 3B-2A=\left[\begin{array}{ccc}9-2& 6-4& 3-6\\ 3-6& 6-4& 9-2\end{array}\right]=\left[\begin{array}{ccc}7& 2& -3\\ -3& 2& 7\end{array}\right]$