(x^3+3x+2)/(x+2)
=x^2-2x+7-12/(x+2)
所以
∫(x^3+3x+2)/(x+2)dx
=∫[x^2-2x+7-12/(x+2)]dx
=x^3/3-x^2+7x-12ln(x+2)+C
C是积分常数