Hey guys I need help with this question

and the answer given in the solution to the question is that since

I know by substituting in values for n in that they all appear divisible by 3, is this a definite rule, is there a proof of this without using induction?

The same goes for , how do we know that this is divisble by 2 for all values of n without induction

If we can't use induction to prove those divisbility by 3 and 2, then isn't the question kinda invalid?

Thanks