Medium MCQ +4 / -1 PYQ · JEE Mains 2024

The function $f: \mathbf{N}-\{1\} \rightarrow \mathbf{N}$; defined by $f(\mathrm{n})=$ the highest prime factor of $\mathrm{n}$, is :

  1. A one-one only
  2. B neither one-one nor onto Correct answer
  3. C onto only
  4. D both one-one and onto

Solution

<p>$$\begin{aligned} & \mathrm{f}: \mathrm{N}-\{1\} \rightarrow \mathrm{N} \\ & \mathrm{f}(\mathrm{n})=\text { The highest prime factor of } \mathrm{n} . \\ & \mathrm{f}(2)=2 \\ & \mathrm{f}(4)=2 \\ & \Rightarrow \text { many one } \\ & 4 \text { is not image of any element } \\ & \Rightarrow \text { into } \end{aligned}$$</p> <p>Hence many one and into</p> <p>Neither one-one nor onto.</p>

About this question

Subject: Mathematics · Chapter: Sets, Relations and Functions · Topic: Sets and Operations

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