∫x[(1-x^2)(1+x^2)]^(1/2)dx
=(1/2)∫[1-(x^2)^2]^(1/2)d(x^2)
=(1/2)∫(1-t^2)^(1/2)dt t=x^2
设t=sinu 0≤u≤pi/2
∴原式=(1/2)∫cosu*cosudu
=(1/4)∫(cos2u+1)du
=sin2u/8+u/4+C
=[x^2*(1-x^4)^(1/2)]/4+[arcsin(x^2)]/4+C