"So you need a reference for 1 + 1?"
No, but then again, that's what calculators are for.
There's a difference between 1+1=2 and solving the recurrence relations
The former does not require any sophistication beyond counting on your fingers. The recurrence, while being comparatively simple and essential to the study of computer science (show me a CS major who does not know what this might represent or how to solve it, and I'll show you a CS major who's not worth his salt), should come along with some sort of explanation or source. There are steps involved in finding a solution (unless you already know the solution).