# Propagation Constant in Transmission Line - Approximation

This is more of a math question but I feel like the maths.stackexchange people won't like these approximations hence I'll stick here.

I'm trying substitute in the conditions for a low-loss transmission line into the general equation for the propogation constant for a transmission line and I'm not getting the correct answer. I think the way I'm using my approximation is downright wrong but I'm not exactly how to apply it. (I think I can't just replace wl+R with just wl since it has something else being multiplied by it)

The correct answer is

• Try expanding the multiplication under the square-root before you start discarding terms. – The Photon Dec 5 '18 at 23:05