Thanks Jilang, that cleared things up for me. I suppose this is a difference between a "Math for Physics" text and a pure mathematics one.
I'm new to the forum, is there a standard for marking questions and posts as [solved] ?
I'm confused by problem 2.31 in mathematical tools for physics.
Problem:
2.31 The Doppler effect for sound with a moving source and for a moving observer have different formulas. The Doppler
effect for light, including relativistic effects is different still. Show that for low speeds they are...