Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Relations and Functions

Question:

f:Z→Z   is given by f(x) = x3 is- 

Options:

injective but not surjective

injective and surjective both

neither injective nor surjective

surjective only

Correct Answer:

injective but not surjective

Explanation:

f:Z→Z   is given by f(x) = x3  

It is seen that for x, y ∈ Z , f(x) = f(y)  ⇒ x3 = y3 ⇒ x =y

So f is injective.

Now, 2 ∈ Z, But there does not exist any element x in Z such that f(x) = x3 = 2

so f is not surjective.

Hence, function f is injective but not surjective.