HCR - Rule of Sarrus

• Source: Wikipedia

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Consider a $3\times 3$ matrix:$M=\left[\begin{array}{ccc}a& b& c\\ d& e& f\\ g& h& i\end{array}\right]$Its determinant will be:$\det (M)=aei+bfg+cdh-ceg-bdi-afh$In general we can use the ‘Rule of Sarrus’ to easily calculate the derminant of any $3\times 3$ matrix, the rule is as follows:

Rule of Sarrus: The determinant of the three columns on the left is the sum of the products along the down-right diagonals minus the sum of the products along the up-right diagonals.