4. ∫f(3x-2)dx = (1/3) ∫ f(3x-2)d(3x-2) = (1/3)F(3x-2)+C7. 令 u=√(e^t-1), 则 t=ln(1+u^2), ∫dt/√(e^t-1) = 2∫<√(e^x-1),√3>du/(1+u^2) = 2[arctanu]<√(e^x-1),√3> = 2[π/3-arctan√(e^x-1)] = π/6 π/3-arctan√(e^x-1) = π/12, arctan√(e^x-1) = π/4 √(e^x-1) = 1, x = ln2.