$=|2 A |^4$
$=\left(2^3| A |\right)^4$
$=2^{12}| A |^4 \Rightarrow 2^{16}$
$|A|=\frac{1}{5 ! 6 ! 7 !} 5 ! 6 !\left|\begin{array}{lll}1 & 6 & 42 \\ 1 & 7 & 56 \\ 1 & 8 & 72\end{array}\right|$
$R _3 \rightarrow R _3 \rightarrow R _2$
$R _2 \rightarrow R _2 \rightarrow R _1$
$|A|=\left|\begin{array}{lll}1 & 8 & 42 \\ 0 & 1 & 14 \\ 0 & 1 & 16\end{array}\right|=2$