|x-4|+3x=5

* Hướng dẫn giải

$\begin{array}{l}\left|x-4\right|+3x=5\left(4\right)\\ -)x\ge 4\Rightarrow \left(4\right)\iff x-4+3x=5\iff x=\frac{9}{4}(tm)\\ -)x<4\Rightarrow \left(4\right)\iff 4-x+3x=5\iff x=\frac{1}{2}(tm)\end{array}$