3. Consider the following recursive method:

    int f(int n) { if (n <= 1) return n + 2; else 

    return 3*f(n-1) - 2*f(n-2); 

   }

   Prove that, for all integers n 0, the call f (n) returns the value 2n + 1. Use strong induction on the value of n. Use strong induction on the value of n. For the (rightfully) picky among you, you may assume that an int value is not limited by any particular bit width.