Prove for k >= 0, r >= 2
F_(k+r) = F_k * F_(r-2) + F_(k+1) * F_(r-1)
I wonder if one should use induction ? If so, I don't know how to do it with two variables.
If not, should I use the Fibonacci definition F_n = F_n-1 + F_n-2 in some way by substitution and renaming
The Attempt at a Solution
Have only tried to substitute index like k + r = m, r-2 = m etc but no luck :(