Answer
$X= \left[\begin{array}{ll}
27/2 & 31/2\\
-4 & 18\\
-29/2 & 6
\end{array}\right]$
Work Step by Step
$4A+3B=-2X$
Multiply both sides with $-\displaystyle \frac{1}{2} .$
$-\displaystyle \frac{1}{2} (4A+3B)=-\frac{1}{2}(-2X)$
$X=-\displaystyle \frac{1}{2} .(4A+3B)$
$X=-\displaystyle \frac{1}{2}\cdot(4\left[\begin{array}{ll}
-3 & -7\\
2 & -9\\
5 & 0
\end{array}\right]+3\displaystyle \left[\begin{array}{ll}
-5 & -1\\
0 & 0\\
3 & -4
\end{array}\right])$
$X=-\displaystyle \frac{1}{2}\cdot(\left[\begin{array}{ll}
-12 & -28\\
8 & -36\\
20 & 0
\end{array}\right]+\displaystyle \left[\begin{array}{ll}
-15 & -3\\
0 & 0\\
9 & -12
\end{array}\right])$
$X=-\displaystyle \frac{1}{2}\cdot\left[\begin{array}{ll}
-27 & -31\\
8 & -36\\
29 & -12
\end{array}\right]$
$X= \left[\begin{array}{ll}
27/2 & 31/2\\
-4 & 18\\
-29/2 & 6
\end{array}\right]$
