PLEASE SOLVE CORRECTLY USING DISCRETE MATH TOOLS ONLY

3. For nN,an is defined as: an=2an1an2 for n2, where a0=1,a1=3 Using strong induction, prove that for all n0,an=2n+1 Also, please explain why you use strong induction for this problem. (15pts) 4. Using induction, prove that: (a) 72n1 is divisible by 48 for every natural number n. (5pts) (b) 72n48n1 is divisible by 2304 for every natural number n. (5 pts)