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\end{bmatrix}  \end{equation}  If we define an operation that is $RCR_ij(A):=R_{ij}$, $RCR_{ij}(A):=R_{ij}$,  remove column, row $ij$ on $A$, then this is expressible as A^{-1}=\begin{bmatrix}   a_{11} R_{11}  & a_{12} R_{12}  & a_{13} R_{13}  \\ a_{21} R_{21}  & a_{22} R_{22}  & a_{23} R_{23}  \\ a_{31} R_{31}  & a_{32} R_{32}  & a_{33} R_{33}  \end{bmatrix}