„Regla Sarrusar“: Munur á milli breytinga

<math>|M|=\begin{vmatrix} {\color{MidnightBlue}a_{11}} & {\color{CadetBlue}a_{12}} & {\color{DarkOrchid}a_{13}} \\ {\color{DarkOrchid}a_{21}} & {\color{MidnightBlue}a_{22}} & {\color{CadetBlue}a_{23}} \\ {\color{CadetBlue}a_{31}} & {\color{DarkOrchid}a_{32}} & {\color{MidnightBlue}a_{33}} \end{vmatrix} = {\color{MidnightBlue}a_{11}a_{22}a_{33}}+{\color{CadetBlue}a_{12}a_{23}a_{31}}+{\color{DarkOrchid}a_{13}a_{21}a_{32}}-{\color{CadetBlue}a_{31}}{\color{MidnightBlue}a_{22}}{\color{DarkOrchid}a_{13}}-{\color{DarkOrchid}a_{32}}{\color{CadetBlue}a_{23}}{\color{MidnightBlue}a_{11}}-{\color{MidnightBlue}a_{33}}{\color{DarkOrchid}a_{21}}{\color{CadetBlue}a_{12}}</math>

 

<math>|M|=\begin{vmatrix} {\color{MidnightBlue}a_{11}} & {\color{CadetBlue}a_{12}} \\ {\color{CadetBlue}a_{21}} & {\color{MidnightBlue}a_{22}} \end{vmatrix} = {\color{MidnightBlue}a_{11}a_{22}} - {\color{CadetBlue}a_{21}a_{12}} </math>