Question

$\left|\begin{array}{ccc}1& 2& 3\\ 0& 2& 4\\ 0& 0& 5\end{array}\right|$.

Answer 1

$\left|\begin{array}{ccc}1& 2& 3\\ 0& 2& 4\\ 0& 0& 5\end{array}\right|$

solving across Row $3$ and $C_3$

$0+0+5\left(2\right)=10$

$\therefore =10$