a^2+2a/a^2-6a+9÷a^2-4/a^2-3a-a/a-2
=a(a+2)/(a-3)^2×a(a-3)/(a+2)(a-2)-a/(a-2)
=(a^2)/(a-3)(a-2)-a/(a-2)
=[a^2-a(a-3)]/(a-3)(a-2)
=3a/(a-3)(a-2)