∫1/(3x+2)^3dx怎么求出来的?参考答案是1/6(3x+2)^3dx,
问题描述：
∫1/(3x+2)^3dx怎么求出来的?参考答案是1/6(3x+2)^3dx,
答
∫1/(3x+2)^3dx=(1/3)∫1/(3x+2)^3d3x=(1/3)∫1/(3x+2)^3d(3x+2)
令(3x+2)=u
=(1/3)∫1/u^3du
=(1/3)∫u^(-3)du
=(1/6)u^(-2)+C
=1/[6(3x+2)^2]+C