[−1−1−21]\left[\begin{array}{rr}-1 & -1 \\-2 & 1\end{array}\right][−1−2−11]
[1−121]\left[\begin{array}{rr}1 & -1 \\2 & 1\end{array}\right][12−11]
[1121]\left[\begin{array}{rr}1 & 1 \\2 & 1\end{array}\right][1211]
[−1−121]\left[\begin{array}{rr}-1 & -1 \\2 & 1\end{array}\right][−12−11]