Lời giải:
\(|x+1|=|x(x+1)|\)
\(\Leftrightarrow |x+1|-|x(x+1)|=0\)
\(\Leftrightarrow |x+1|-|x||x+1|=0\)
\(\Leftrightarrow |x+1|(1-|x|)=0\)
\(\Rightarrow \left[\begin{matrix} |x+1|=0\\ 1-|x|=0\end{matrix}\right.\Rightarrow \left[\begin{matrix} x+1=0\\ |x|=1\end{matrix}\right.\Rightarrow \left[\begin{matrix} x=-1\\ x=\pm 1\end{matrix}\right.\)