Ta thấy:
\(\left\{{}\begin{matrix}\left|x+1\right|\ge0\\\left|x-3\right|\ge0\end{matrix}\right.\)
\(\Rightarrow\left|x+1\right|-\left|x-3\right|\ge0\)
Mà \(\left|x+1\right|-\left|x-3\right|\ge0\)
\(\Rightarrow\left\{{}\begin{matrix}\left|x+1\right|=0\\\left|x-3\right|=0\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}x=-1\\x=3\end{matrix}\right.\)
Không chắc :))
