please explain

4. Induction (15 pt] Consider Fibonacci numbers Fo,F1,F2, ... defined by the following rule F = 1, F1 = 1, Fn = Fn-1 + Fn-2. In this problem, we will confirm that this sequence grows exponentially fast and obtain bounds on this growth. a) Use induction to prove that in 2 20.5n for n 2 2. b) Find a constant c 0