\(\dfrac{3x^3+6x^2}{x^3+2x^2+x+2}=\dfrac{3x^2\left(x+2\right)}{x^2\left(x+2\right)+\left(x+2\right)}=\dfrac{3x^2\left(x+2\right)}{\left(x^2+1\right)\left(x+2\right)}=\dfrac{3x^2}{x^2+1}\)
Vì \(3x^2\ge0,x^2+1>0\Rightarrow\dfrac{3x^2}{x^2+1}\ge0\)
Vậy phân thức \(\dfrac{3x^3+6x^2}{x^3+2x^2+x+2}\) luôn không âm