$B=\left | x^2-x+1 \right |+\left | x^2-x-2 \right |=\left | x^2-x+1 \right |+\left | -x^2+x+2 \right |\geq \left | x^2-x+1-x^2+x+2 \right |=\left | 3 \right |=3\Rightarrow minB=3\Leftrightarrow (x^2-x+1)(2-x^2+x)\geq 0\Leftrightarrow -1\leq x\leq 2$
- bovuotdaiduong yêu thích