Determinant of $\left[\begin{array}{cc}2 & 3\\5 & 6\end{array}\right]$

Calculate $\left|\begin{array}{cc}2 & 3\\5 & 6\end{array}\right|$.

The determinant of a 2x2 matrix is $\left|\begin{array}{cc}a & b\\c & d\end{array}\right| = a d - b c$.

$\left|\begin{array}{cc}2 & 3\\5 & 6\end{array}\right| = \left(2\right)\cdot \left(6\right) - \left(3\right)\cdot \left(5\right) = -3$

$\left|\begin{array}{cc}2 & 3\\5 & 6\end{array}\right| = -3$A