2. (a) Use induction on n to prove that for all integers n 0, the value 4n + l is not divisible by 3. (20 points) (b) Consider the infinite sequence of integers fo, fi, f2, ..., defined by fo-1, f 2 and 3 fn-nn-2 for all n 2 2. Use induction on n to prove thatfor all n 2 1. (20 points) n > 2. Use induction on n to prove that f>