Question

Find the values of $x,y$ and $z$ if $\left[\begin{array}{cc}x+2& 6\\ 3& 5z\end{array}\right]=\left[\begin{array}{cc}-5& y^2+y\\ 3& -20\end{array}\right]$

Answer 1

$\left[\begin{array}{cc}x+2& 6\\ 3& 5z\end{array}\right]=\left[\begin{array}{cc}-5& y^2+y\\ 3& -20\end{array}\right]$

$x+2=-55z=-20$

$x=-5-2z=-20/5$

$x=-7z=-4$

$y^2+y=6$

$y^2+y-6=0$

$y^2+3y-2y-6=0$

$y(y+3)-2(y+3)=0$

$(y+3)=0(y-2)=0$

So $y=-3,y=2$