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