##### Item1.2.5.1.c

The reduced row echelon form is

\begin{equation*} \left[\begin{array}{rrrrr} 1 \amp 0 \amp 0 \amp 0 \amp 1 \\ 0 \amp 1 \amp 0 \amp 0 \amp 3 \\ 0 \amp 0 \amp 1 \amp 0 \amp -2 \\ 0 \amp 0 \amp 0 \amp 1 \amp 0 \end{array}\right]\text{,} \end{equation*}

which shows that there is a single solution $$(1,3,-2,0)$$ and that every variable is a basic variable.

in-context