How do you find the determinant of ((-9, -7), (4, 5))?

Feb 9, 2016

The determinant is $- 17$.

Explanation:

For a $2 \times 2$ matrix

$A = \left(\begin{matrix}a & b \\ c & d\end{matrix}\right)$,

the determinant can be computed as

$| A | = a \cdot d - b \cdot c$

$\left\mid \left(\begin{matrix}- 9 & - 7 \\ 4 & 5\end{matrix}\right) \right\mid = - 9 \cdot 5 - \left(- 7\right) \cdot 4 = - 45 + 28 = - 17$