Prove Fibonacci formula with induction?

[Sven]

Homework Statement

I'm trying to prove the Fibonacci formula with induction, but I'm having difficulties. This is what I'm trying to prove:

http://www.psc-consulting.ca/fenske/cpjav17e.gif

Homework Equations

The Attempt at a Solution

So I did a base case, n=1. It worked, so move to induction. Now, I have absolutely *no* idea how to get this to work, even start? So I took it and added n+1 to both sides. Then what? I tried multiplying by sqrt(5) to make it a lil simpler (dunno if I'm allowed to do that) but I'm really not sure where to go next. Any help would be very much appreciated.

 

[willem2]

Try to assume that the formula is true for f(n) and for f(n-1).

what base case(s) do you have to prove?