Question:
$2 y-3 z=0$
$x+3 y=-4$
$3 x+4 y=3$
Solution:
These equations can be written as
$0 x+2 y-3 z=0$
$x+3 y+0 z=-4$
$3 x+4 y+0 z=3$
$D=\left|\begin{array}{ccc}0 & 2 & -3 \\ 1 & 3 & 0 \\ 3 & 4 & 0\end{array}\right|$
$=0(0-0)-2(0-0)-3(4-9)$
$=15$
$D_{1}=\left|\begin{array}{ccc}0 & 2 & -3 \\ -4 & 3 & 0 \\ 3 & 4 & 0\end{array}\right|$
$=0(0-0)-2(0-0)-3(-16-9)$
$=75$
$D_{2}=\left|\begin{array}{ccc}0 & 0 & -3 \\ 1 & -4 & 0 \\ 3 & 3 & 0\end{array}\right|$
$=0(0-0)-0(0-0)-3(3+12)$
$=-45$
$D_{3}=\left|\begin{array}{ccc}0 & 2 & 0 \\ 1 & 3 & -4 \\ 3 & 4 & 3\end{array}\right|$
$=0(9+16)-2(3+12)-0(4-9)$
$=-30$
Now,
$x=\frac{D_{1}}{D}=\frac{75}{15}=5$
$y=\frac{D_{2}}{D}=\frac{-45}{15}=-3$
$z=\frac{D_{3}}{D}=\frac{-30}{15}=-2$
$\therefore x=5, y=-3$ and $z=-2$