## Algebra and Trigonometry 10th Edition

$-5$
The determinant of a $2 \times 2$ matrix can be computed by using the formula $det =ps-qr$ where $det =\begin{vmatrix}p & q \\r & s\end{vmatrix}$ So, $\begin{vmatrix} 1& 0 &0 \\-4 & -1 & 0 \\ 5 &1 & 5\end{vmatrix}=1 \begin{vmatrix} -1 & 0 \\1 & 5\end{vmatrix}$ or, $=1[(-1)(5)-0]$ or, $=-5$