Ta có :
\(\dfrac{x+3}{\left(x+2\right)\left(x-2\right)}.\dfrac{8-12x+6x^2-x^3}{9\left(x+3\right)}=\dfrac{-\left(x^3-6x^2+12x-8\right)}{9\left(x+2\right)\left(x-2\right)}=\dfrac{-\left(x-2\right)^3}{9\left(x+2\right)\left(x-2\right)}=\dfrac{-\left(x-2\right)^2}{9\left(x+2\right)}\)


