求∫xe^x/(√e^x-1)dx

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求∫xe^x/(√e^x-1)dx

求∫xe^x/(√e^x-1)dx
求∫xe^x/(√e^x-1)dx

求∫xe^x/(√e^x-1)dx

如下

设 e^x-1=t^2, 则e^xdx=2tdt ,∫xe^x/(√e^x-1)dx=∫ln(t^2+1)2tdt/t=2∫ln(t^2+1)dt
=2tln(t^2+1) -2∫tdln(t^2+1) =2tln(t^2+1) -2∫2t^2dt/(t^2+1)= 2tln(t^2+1) -4t+4∫dt/(t^2+1)
=2tln(t^2+1) -4t+4arctant+C,(t=√e^x-1)

令 y = √e^x-1
x = ln (y^2 + 1)
∫xe^x/(√e^x-1)dx
= ∫ ln (y^2 + 1) * (y^2+1) / y * 2y / (y^2+1) dy + c
= 2y ln(y^2+1) - 4y + 4arctany + c
= 2 (√e^x-1) x - 4(√e^x-1) + 4arctan (√e^x-1) + c