假设不定积分∫1/√(1+t^3)dt=F(t)则F'(t)=1/√(1+t^3)定积分<0→x^2>∫1/√(1+t^3)dt=F(x^2)-F(0)[定积分<0→x^2>∫1/√(1+t^3)dt]'=[F(x^2)-F(0)]'=F'(x^2)*2x-0=2x/√(1+x^6)同理设G(t)=∫1/(√1+t^4)dt原积分=G(x^3)-G(x^2)原积分'=G'(x^3)*3x^2-G'(x^2)*2x=3x^2/√(1+x^12)-2x/√(1+x^8)