Question

If $A=\left[\begin{array}{cc}9& 2\\ 6& 12\end{array}\right],B=\left[\begin{array}{cc}3& 4\\ 1& 3\end{array}\right]andC=\left[\begin{array}{cc}6& 3\\ 1& 3\end{array}\right]$, find X such that A+B-C=3X

Answer 1

$A+B-C=3X$

$\left[\begin{array}{cc}9+3-6& 2+4-3\\ 6+1-1& 12+3-3\end{array}\right]=3X$

$3X=\left[\begin{array}{cc}6& 6\\ 6& 12\end{array}\right]$

$X=\frac{1}{3}\left[\begin{array}{cc}6& 3\\ 6& 12\end{array}\right]$

$X=\left[\begin{array}{cc}2& 1\\ 2& 4\end{array}\right]$