Question

If $A=\left[\begin{array}{cc}1& 2\\ 4& 2\end{array}\right]$ ,then find the value of $|2A|$:

Answer 1

$A=\left[\begin{array}{cc}1& 2\\ 4& 2\end{array}\right]$

$2A=\left[\begin{array}{cc}2& 4\\ 8& 4\end{array}\right]$

$|2A|=\left|\begin{array}{cc}2& 4\\ 8& 4\end{array}\right|=8-32=-24$