Possible Duplicate:
Best way to integrate $ \int_0^\infty \frac{e^{-at} - e^{-bt}}{t} \text{d}t $
Compute the improper integral: $$I=\int_{0}^{\infty} \frac{e^{-a x} - e^{-b x}}{x} dx$$
Possible Duplicate:
Best way to integrate $ \int_0^\infty \frac{e^{-at} - e^{-bt}}{t} \text{d}t $
Compute the improper integral: $$I=\int_{0}^{\infty} \frac{e^{-a x} - e^{-b x}}{x} dx$$