|2x|=x-6

* Hướng dẫn giải

$\begin{array}{l}\left|2x\right|=x-6\left(5\right)\\ +)x\ge 0\Rightarrow \left(5\right)\iff 2x=x-6\iff x=-6(ktm)\\ +)x<0\Rightarrow \left(5\right)\iff -2x=x-6\iff x=2(ktm)\Rightarrow S=\varnothing \end{array}$