Medium INTEGER +4 / -1 PYQ · JEE Mains 2025

Let $A=\{1,2,3\}$. The number of relations on $A$, containing $(1,2)$ and $(2,3)$, which are reflexive and transitive but not symmetric, is _________.

Answer (integer) 3

Solution

<p>Transitivity</p> <p>$(1,2) \in \mathrm{R},(2,3) \in \mathrm{R} \Rightarrow(1,3) \in \mathrm{R}$</p> <p>For reflexive $(1,1),(2,2)(3,3) \in R$</p> <p>Now $(2,1),(3,2),(3,1)$</p> <p>$(3,1)$ cannot be taken</p> <p>(1) $(2,1)$ taken and $(3,2)$ not taken</p> <p>(2) $(3,2)$ taken and $(2,1)$ not taken</p> <p>(3) Both not taken</p> <p>therefore 3 relations are possible.</p>

About this question

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

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