Medium MCQ +4 / -1 PYQ · JEE Mains 2023

Let $\mathrm{R}$ be a relation on $\mathrm{N} \times \mathbb{N}$ defined by $(a, b) ~\mathrm{R}~(c, d)$ if and only if $a d(b-c)=b c(a-d)$. Then $\mathrm{R}$ is

  1. A symmetric and transitive but not reflexive
  2. B reflexive and symmetric but not transitive
  3. C transitive but neither reflexive nor symmetric
  4. D symmetric but neither reflexive nor transitive Correct answer

Solution

Given, $(a, b) R(c, d) \Rightarrow a d(b-c)=b c(a-d)$ <br/><br/><b>Symmetric :</b> <br/><br/>(c, d) $R(a, b) \Rightarrow \operatorname{cb}(\mathrm{d}-\mathrm{a})=\mathrm{da}(\mathrm{c}-\mathrm{b}) $ <br/><br/>$\Rightarrow$ Symmetric. <br/><br/><b>Reflexive :</b> <br/><br/>(a, b) R (a, b) $\Rightarrow a b(b-a) \neq b a(a-b) $ <br/><br/>$\Rightarrow$ Not reflexive. <br/><br/><b>Transitive : </b> <br/><br/>$(2,3) \mathrm{R}(3,2)$ and $(3,2) \mathrm{R}(5,30)$ but <br/><br/>$((2,3),(5,30)) \notin \mathrm{R} $ <br/><br/>$\Rightarrow$ Not transitive.

About this question

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

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