[3−12−1227]\left[\begin{array}{rr}3 & -12 \\-12 & 27\end{array}\right][3−12−1227]
[312−1227]\left[\begin{array}{rr}3 & 12 \\-12 & 27\end{array}\right][3−121227]
[3−121227]\left[\begin{array}{rr}3 & -12 \\12 & 27\end{array}\right][312−1227]
[3−1212−27]\left[\begin{array}{rr}3 & -12 \\12 & -27\end{array}\right][312−12−27]