令t=√(e^x-1),则x=ln(t^2+1),dx=2t/(t^2+1)dt
原式=∫2t^2/(t^2+1)dt
=2∫[1-1/(t^2+1)]dt
=2(t-arctant)+C
=2√(e^x-1)-2arctan[√(e^x-1)]+C,其中C是任意常数
令 √(eˣ-1) = u, 则 x = ln(1+u^2), dx = 2udu/(1+u^2)
∫√(eˣ-1)dx = ∫2u^2du/(1+u^2) = 2∫(1+u^2-1)du/(1+u^2)
= 2∫du - 2∫du/(1+u^2) = 2u - 2arctanu + C
= 2√(eˣ-1) - 2arctan√(eˣ-1) + C
只要令√e^x=t,则x=ln(t^2)=2lnt,dx=2/t dt。代入后原积分=∫(t-1)*2/t dt=2∫(1-1/t)dt=…….
等于根号e^-1)x+c