Giải phương trình |2x+1|-|5x-2|=3

* Hướng dẫn giải

$\begin{array}{l}\left|2x+1\right|-\left|5x-2\right|=3\left(28\right)\\ *)x<-\frac{1}{2}\Rightarrow \left(28\right)\iff -2x-1-2+5x=3\iff x=2(ktm)\\ *)-\frac{1}{2}\le x\le \frac{2}{5}\Rightarrow \left(28\right)\iff 2x+1-2+5x=3\iff x=\frac{4}{7}(ktm)\\ *)x>\frac{2}{5}\Rightarrow \left(28\right)\iff 2x+1-5x+2=3\iff x=0(ktm)S=\varnothing \end{array}$