Question

Find $x$ if $\left[\begin{array}{ccc}1& 0& 0\\ 2& 3& 4\\ 5& -6& x\end{array}\right]=45$

Answer 1

We have the given matrix,

$\left|\begin{array}{ccc}1& 0& 0\\ 2& 3& 4\\ 5& -6& x\end{array}\right|=45Forthevalueofxwecansolvethefolowingmatrix\Rightarrow 1\left|\begin{array}{cc}3& 4\\ -6& x\end{array}\right|=45\Rightarrow 3x-24=45\Rightarrow 3x=45+24\Rightarrow 3x=69\Rightarrow x=\frac{69}{3}\Rightarrow x=23$

Hence

$x=23$