[−21−2−1]\left[\begin{array}{cc}-2 & 1 \\-2 & -1\end{array}\right][−2−21−1]
[21−2−1]\left[\begin{array}{cc}2 & 1 \\-2 & -1\end{array}\right][2−21−1]
[21−21]\left[\begin{array}{cc}2 & 1 \\-2 & 1\end{array}\right][2−211]
[−2−1−2−1]\left[\begin{array}{ll}-2 & -1 \\-2 & -1\end{array}\right][−2−2−1−1]
