The matrix is in reduced echelon form. $$\left. \left[ \begin{array} { c c c c }
1 & 0 & 0 & 0 \
0 & 0 & 1 & 0 \
0 & 1 & 0 & 0 \
0 & 0 & 0 & 1
\end{array} \right] \quad \begin{array} { r }
1 \
- 7 \
1\
-8
\end{array} \right]$$

Question

The matrix is in reduced echelon form. $$\left. \left[ \begin{array} { c c c c } 
1 & 0 & 0 & 0 \
0 & 0 & 1 & 0 \
0 & 1 & 0 & 0 \
0 & 0 & 0 & 1
\end{array} \right] \quad \begin{array} { r } 
1 \
- 7 \
1\
-8
\end{array} \right]$$

Quizplus · Accepted Answer

For a matrix to be in reduced row echelon form, each leading entry must be in a column to the right of the leading entry in the previous row. Here, the second row's leading entry (in the third column) is to the right of the third row's leading entry (in the second column), which violates this rule.

The Matrix Is in Reduced Echelon Form