# How do you find the determinant of [(-5,7), (5,8)]?

$\det \left(\begin{matrix}- 5 & 7 \\ 5 & 8\end{matrix}\right) = | \left(- 5 , 7\right) , \left(5 , 8\right) |$
$= \left(- 5\right) \left(8\right) - \left(5\right) \left(7\right)$
$= - 40 - 35$
$= - 75$