Ta có \(\left|x-1\right|\ge0\forall x\)

\(\left|x-4\right|\ge0\forall x\)

\(\Rightarrow\left|x-1\right|+\left|x-4\right|\ge0\forall x\)

Mà theo bài ra \(\left|x-1\right|+\left|x-4\right|=3x\)

Nên \(3x\ge0\Rightarrow x\ge0\)

Khi đó ta có \(x-1+x-4=3x\)

\(\Rightarrow2x-5=3x\)

\(\Rightarrow-5=x\)

Vậy x=-5

1. I have fewer textbook than my elder brother

My elder brother has __more textbook than me__________

2. Vietnamese students have fewer vacations than American ones.

American students have more vacation than Vietnameses students_

3. Mr.Lam also has ten days off for his summer vacation.

Mr.Lam also has a _ten-day off summer vacation__________