$$\left. \begin{array} { l } { A = | \begin{array} { l } { - 2 } & { - 10 } & { - 20 } \end{array} } \end{array} \right.$$
$A=2|l|$
$l\in \mathrm{C}$
$A=2|l|$
$l\in \mathrm{R}$
