## Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

$ad-bc$
The determinant for a 2 by 2 matrix can be computed as: $Determinant (Det)= \begin{vmatrix} a & b \\ c & d \\ \end{vmatrix}=ad-bc$ Let us consider an example: $Det=\begin{vmatrix} 6 & 4 \\ -1 & 3 \\ \end{vmatrix}=(6)(3) -(4)(-1)=18+4=22$ So, our answer is: $ad-bc$