∫ √x/(√x- 3^√x) dx 换元,x=t^6=∫ t^3 / (t^3-t^2) d(t^6)=∫ t^3(6t^5) / (t^3-t^2) dt=6∫ t^6/(t-1) dt=6∫ (t^6-1+1)/(t-1) dt=6∫ (t^5+t^4+t^3+t^2+t+1) dt + 6∫ 1/(t-1) d(t-1)=6(t^6/6+t^5/5+t^4/4+t^...