履修者各位:
(誤) $ \left| \begin{array}{cc} 7 & -5 \\ 6 & 3 \end{array} \right| = \left| \begin{array}{cc} 7+3 & -5 \\ 6+3 & 3 \end{array} \right| = \left| \begin{array}{cc} 7 & -5 \\ 6 & 3 \end{array} \right| + \left| \begin{array}{cc} 3 & -5 \\ 3 & 3 \end{array} \right| =\cdots $
(正) $ \left| \begin{array}{cc} 7 & -5 \\ 6 & 3 \end{array} \right| = \left| \begin{array}{cc} 4+3 & -5 \\ 3+3 & 3 \end{array} \right| = \left| \begin{array}{cc} 4 & -5 \\ 3 & 3 \end{array} \right| + \left| \begin{array}{cc} 3 & -5 \\ 3 & 3 \end{array} \right| =\cdots $