\(\left|-x+5\right|\ge0\forall x;\left|y-1\right|\ge0\forall y\\ \Rightarrow\left|-x+5\right|+\left|y-1\right|\ge0\forall x,y\)
Mà \(\left|-x+5\right|+\left|y-1\right|\le0\)
\(\Rightarrow\left\{{}\begin{matrix}\left|-x+5\right|=0\\\left|y-1\right|=0\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}-x+5=0\\y-1=0\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x=5\\y=1\end{matrix}\right.\)