8x³(x-3)-12x²(x-3)=(8x³-12x²)(x-3)=4x²(2x-3)(x-3)
(x^2+3x)/(x^2+2x)-(x^2-4)/(x^2+4x+4)
=x(x+3)/x(x+2)-(x-2)(x+2)/(x+2)^2
=(x+3)/(x+2)-(x-2)/(x+2)
=[(x+3)-(x-2)]/(x+2)
=5/(x+2)