二曲线围成面积在[0,1]上
0≤x≤1时,有x^3≤x^(1/3)
∴A=∫<0,1>[x^(1/3)-x^3]dx
=<0,1>[3/4*x^(4/3)-x^4/4]
=[3/4*1-1/4]-0
=1/2