Item1.2.5.1.a
The reduced row echelon form is
\begin{equation*} \left[\begin{array}{rr|r} 1 \amp 0 \amp -1 \\ 0 \amp 1 \amp 2 \\ 0 \amp 0 \amp 0 \\ \end{array}\right]\text{,} \end{equation*}and there is a single solution. Every variable is basic.
The reduced row echelon form is
\begin{equation*} \left[\begin{array}{rr|r} 1 \amp 0 \amp -1 \\ 0 \amp 1 \amp 2 \\ 0 \amp 0 \amp 0 \\ \end{array}\right]\text{,} \end{equation*}and there is a single solution. Every variable is basic.