Mathematics - Matrices Question with Solution | TestHub

$AB=I\Rightarrow A(10B)=10\mathrm{I}$ $\Rightarrow \left[\begin{array}{ccc}1& -1& 1\\ 2& 1& -3\\ 1& 1& 1\end{array}\right]\left[\begin{array}{ccc}4& 2& 2\\ -5& 0& \alpha \\ 1& -2& 3\end{array}\right]=\left[\begin{array}{ccc}10& 0& 5-\alpha \\ 0& 10& \alpha -5\\ 0& 0& 5+\alpha \end{array}\right]=10\left[\begin{array}{lll}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\end{array}\right]$ if $\alpha =5$.