(2/(9+3a) - 4/(9-a^2)+1/(9-3a))*(9-6a+a^2)

2/3(3+a)-4/(3-a)(3+а)+1/3(3-a)=(6-2a-12+3+a)/(3(3-a)(3+a)=(-3-a)/(3(3-a)(3+a)==-(3+a)/3(3-a)(3+a)=1/3(a-3)1/3(a-3)*(a-3)²=(a-3)/3