please help

6. (a) [4 points] Define what it means to say that a function f : A - B is injective (1-1), surjective (onto), and bijective. (b) Consider the function f : N - N defined by the formula f(n) = n2. (i) [2 points] Is f injective or surjective or both? (ii) [2 points] If possible, find a left inverse to the function f, that is, a function g : N - N such that go f = id. (iii) [2 points] If possible, find a right inverse to the function f, that is, a function g : N - N such that fog = id