Gọi PT kia là (1) nhé
Lập bảng xét dấu
\(y\) \(0\) \(2\)
\(\left|y\right|\) \(-y\) \(0\) \(y\) II \(y\)
\(\left|y-2\right|\) \(2-y\) II \(2-y\) \(0\) \(y-2\)
VT \(2-2y\) \(2\) \(2y-2\)
TH1: \(y\le0\Rightarrow\left\{{}\begin{matrix}\left|y\right|=-y\\\left|y-2\right|=2-y\end{matrix}\right.\)
(1) \(\Leftrightarrow-y+2-y=2-2y\)
TH2: \(0\le y\le2\Rightarrow\left\{{}\begin{matrix}\left|y\right|=y\\\left|y-2\right|=2-y\end{matrix}\right.\)
(1) \(\Leftrightarrow y+2-y=2\)
TH3: \(y>2\Rightarrow\left\{{}\begin{matrix}\left|y\right|=y\\\left|y-2\right|=y-2\end{matrix}\right.\)
(1) \(\Leftrightarrow y+y-2=2y-2\)
Vậy \(0\le y\le2\)
