How to find inverse matrix?
The inverse matrix of $2 \times 2$ matrix is $
\mathrm{A}^{-1}=\frac{1}{\mathrm{ad}-\mathrm{bc}}\left[\begin{array}{cc}
d & -b \\
-c & a
\end{array}\right]
$.
The inverse of $3 \times 3$ Matrix can be caluculated by the formula $A^{-1}=\frac{1}{|A|} \cdot \operatorname{adj}(A)$