Answer
$-5$
Work Step by Step
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, $=-5$
