Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Relations and Functions

Question:

Let $A = \{x∈R:-1≤x≤1\}$. Then, the mapping $f:A→A$ given by $f (x) = x|x|$, is

Options:

injective but not surjective

surjective but not injective

bijective

none of these

Correct Answer:

bijective

Explanation:

We have,

$f(x)=x|x|=\left\{\begin{matrix}x^2,&x≥0\\-x^2,&x<0\end{matrix}\right\}$

The graph f (x) is shown in Fig.

Clearly, f is bijective.