I am writing a paper, and I need to display an elimination matrix during the steps of finding a determinant.
\[
A =\begin {bmatrix}
a_{11} & a_{12} \\
a_{21} & a_{22}
\end {bmatrix}
\]
The above gives me a bracketed 2 x 2 Matrix. What I need to do, is display a subsequent elimination matrix where the ith row and jth column is lined out. I need to line out any row and any column I desire.