Finite Math Examples

$[\begin{array}{c} 1 & 9 & 0 & 12 \\ 0 & 1 & 3 & - 8 \\ 0 & 0 & 1 & 0 \end{array}]$

Step 1

Transpose the matrix by switching its rows to columns.

$[\begin{array}{c} 1 & 0 & 0 \\ 9 & 1 & 0 \\ 0 & 3 & 1 \\ 12 & - 8 & 0 \end{array}]$