Let's check the given function f(n) = 3n + 4, ∀ n ∈ N for one-to-one and onto: Injective: Let's say 3n+4=k⇒n=
k−4
3
It means that for every value of k, we will get only a single value of n, therefore the function is injective. Surjective: Since n=
k−4
3
, not all values of k will give n ∈ N. So, the function is not surjective. Bijective: Since the function is injective but not surjective, it is not bijective. So, the function f is only injective.