∫xdx/(√(1+x^(2/3)))

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∫xdx/(√(1+x^(2/3)))∫xdx/(√(1+x^(2/3)))∫xdx/(√(1+x^(2/3)))设x=tan³t,则dx=3tan²t*sec²tdt,

∫xdx/(√(1+x^(2/3)))
∫xdx/(√(1+x^(2/3)))

∫xdx/(√(1+x^(2/3)))
设x=tan³t,则dx=3tan²t*sec²tdt,cost=1/√(1+x^(2/3))
∴原式=∫tan³t*3tan²t*sec²tdt/sect
=3∫(tant)^5*sectdt
=3∫(sint)^5/(cost)^6dt
=-3∫(sint)^4/(cost)^6d(cost)
=-3∫(1-cos²t)²/(cost)^6d(cost)
=-3∫[1/(cost)^6-2/(cost)^4+1/cos²t]d(cost)
=-3[(-1/5)/(cost)^5+(2/3)/cos³t-1/cost]+C (C是积分常数,cost=1/√(1+x^(2/3)))