|x(x+1)|=|(x+1)(mx-2m-1)|
<=> |x(x+1)|-|(x+1)(mx-2m-1)| = 0
<=> |x|. |x+1| - |x+1|. |mx-2m-1| = 0
<=> |x+1|. (|x|- |mx-2m-1|) =0
,<=> \(\left[ \begin{array}{l}x+1=0\\|x|- |mx-2m-1|=0\end{array} \right.\)
<=> \(\left[ \begin{array}{l}x=-1\\|x|= |mx-2m-1|\end{array} \right.\)