Ta có :
\(\left|x-1\right|\ge0\)
\(\left|x-4\right|\ge0\)
\(\Rightarrow\)\(\left|x-1\right|+\left|x-4\right|\ge0\)
Mà \(\left|x-1\right|+\left|x-4\right|=3x\)
\(\Rightarrow\)\(3x\ge0\)
\(\Rightarrow\)\(x\ge0\)
PT \(\Leftrightarrow\)\(x-1+x-4=3x\)
\(\Leftrightarrow\)\(2x-5=3x\)
\(\Leftrightarrow\)\(3x-2x=-5\)
\(\Leftrightarrow\)\(x=-5\)
Vậy \(x=-5\)
Chúc bạn học tốt ~