Question

Let f: R → R be defined as f(x) = x^4. Choose the correct answer.
(A) f is one-one onto 

(B) f is many-one onto
(C) f is one-one but not onto 

(D) f is neither one-one nor onto

Answer 1

Consider an element 2 in co-domain R. It is clear that there does not exist any x in domain R such that f(x) = 2.
∴ f is not onto.
Hence, function f is neither one – one nor onto.

The correct answer is D.