Có
\(\left\{{}\begin{matrix}\left|x^2-4\right|\ge0\forall x\\\left(2y-6\right)^4\ge0\forall y\end{matrix}\right.\)
=> \(\left|x^2-4\right|+\left(2y-6\right)^2\ge0\forall x;y\)
Do đó để \(\left|x^2-4\right|+\left(2y-6\right)^2=0\)
\(\Leftrightarrow\left\{{}\begin{matrix}x^2-4=0\\2y-6=0\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}\left(x-2\right)\left(x+2\right)=0\\y=3\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x=2\\y=3\end{matrix}\right.\\\left\{{}\begin{matrix}x=-2\\y=3\end{matrix}\right.\end{matrix}\right.\)
