Enter values for the matrix.
Enter fractions with a slash, as "3/4" or "-10/3".

### Reduce the column containing the red cell.

$$\left[\begin{array}{rrr|r}\large\color{Red} {-4} & -3 & -2 & 12 \\ 0 & -3 & 0 & 0 \\ 1 & -4 & -5 & -25\end{array}\right]\begin{array}{ll}\large\phantom{1} & \\ \phantom{1} & \\ \phantom{1} & \end{array}$$