Answer
$\left| \begin{matrix}
3 & 0 & 0 \\
2 & 1 & -5 \\
2 & 5 & -1 \\
\end{matrix} \right|=72$.
Work Step by Step
Expand with ${{R}_{1}}$
$\begin{align}
& \left| \begin{matrix}
3 & 0 & 0 \\
2 & 1 & -5 \\
2 & 5 & -1 \\
\end{matrix} \right|=3\left( -1-\left( -25 \right) \right) \\
& =3\left( 24 \right) \\
& =72
\end{align}$
