Question

Answer 1

\(\Leftrightarrow\left\{{}\begin{matrix}\left|x\right|+4\left|y\right|=18\\12\left|x\right|+4\left|y\right|=40\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}\left|x\right|=2\\\left|y\right|=4\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x\in\left\{2;-2\right\}\\y\in\left\{4;-4\right\}\end{matrix}\right.\)

Answer 2