\(2\,u^2\)

$$
\begin{array}{l}
{\left[\begin{array}{ll}
4 & 2 \\
1 & 1
\end{array}\right] \rightarrow \operatorname{det}\left[\begin{array}{ll}
4 & 2 \\
1 & 1
\end{array}\right]=4-2=2} \\
\therefore \text { Area of parallelogram }=2 \times 1
=2 u^{2}
\end{array}
$$