7. Consider the following recurrence. f(0; a, b) a f(n; a, b-f(n -1;b, a +b) (a) Prove using mathematical induction that for any n N if n > l then f(n: a, b) f(n-1; a, b) + f(n- (b) Prove using the strong form of mathematical induction that for any n N, Fn- f(n; 0,1). You should 2;a, b) use the previous result in your proof