Item1.2.5.3.b

\(\left[\begin{array}{rrr|r} 1 \amp 0 \amp -2 \amp 0 \\ 0 \amp 1 \amp 1 \amp 0 \\ 0 \amp 0 \amp 0 \amp 1 \\ \end{array}\right]\text{.}\)

in-context