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Question: Answered & Verified by Expert
Let $\mathrm{A}=\{\mathrm{x} \in \mathbb{R}:-1 \leq \mathrm{x} \leq 1\} \& \mathrm{f}: \mathrm{A} \rightarrow \mathrm{A}$ be a mapping defined by $\mathrm{f}(\mathrm{x})=\mathrm{x}|\mathrm{x}| .$ Then $\mathrm{f}$ is
MathematicsFunctionsWBJEEWBJEE 2020
Options:
  • A injective but not surjective
  • B surjective but not injective
  • C neither injective nor surjective
  • D bijective
Solution:
1831 Upvotes Verified Answer
The correct answer is: bijective
Hint:
$f(x)=x|x|=\left\{\begin{array}{c}-x^{2} x \in[-1,0) \\ x^{2} x \in[0,1]\end{array}\right.$

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