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 $A^{-1}=\frac{1}{|A|} \cdot \operatorname{adj}(A)$
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