一道积分题 ∫1/(x+x^1/3)dx

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一道积分题 ∫1/(x+x^1/3)dx
一道积分题 ∫1/(x+x^1/3)dx

一道积分题 ∫1/(x+x^1/3)dx
设t³=x,则dx=3t²dt
∫1/(x+x^1/3)dx
=∫1/(t^3+t)*3t^2dt
=∫3t/(t^2+1)dt
=∫3/2*d(t^2+1)/(t^2+1)
=3/2*ln(t^2+1)+C
=3/2*ln[x^(2/3)+1]+C

∫1/(x+x^(1/3))dx
设t³=x,dx=3t²dt
∫1/(x+x^(1/3))dx
=∫3t²dt/(t³+t)
=3∫tdt/(t²+1)
=3/2∫dt²/(t²+1)
=3/2ln|1+t²|+C
=3/2ln|1+x^(2/3)|+C

令t³=x,则dx=3t²dt
∫1/(x+x^1/3)dx
=∫1/(t³+t)*3t²dt
=∫3t/(t²+1)dt
=∫1.5*[d(t²+1)]/(t²+1)
=1.5ln(t²+1)+C
=1.5ln[x^(2/3)+1]+C