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问题: 大学作业30

求不定积分
∫√x/[x^(4/3)+1]

解答:

解:令X=t^4,则dt=4t^3,于是 ∫{(√x)/[x^(3/4)+1]}dx
=4∫[t^5/(t^3+1)]dt=4∫[t^2-t^2/(t^3+1)]dt
=4[∫t^2dt-(1/3)∫d(t^3+1)/(t^3+1)]
=4[t^3/3-(1/3)ln(t^3+1)]+c
=(4/3){x^(3/4)-ln[x^(3/4)+1]}+c