Mathematics · Sets and Relations

JEE Main 2025 — 2 April, Morning Shift — Question 29

Let AA be the set of all function f:Z→Zf: \mathbb{Z} \rightarrow \mathbb{Z} and RR be a relation on AA such that

R={(f,g}:f(0)=g(1)R=\{(f, g\}: f(0)=g(1) and f(1)=g(0)f(1)=g(0). Then RR is:

  1. Option A:

    Symmetric and transitive but not reflective

  2. Option B:

    Reflexive but neither symmetric nor transitive

  3. Option C:

    Transitive but neither reflexive nor symmetric

  4. Option D:

    Symmetric but neither reflective nor transitive

    Correct

Answer: D

Step-by-step solution

For RR to be reflexive, ( f,ff, f ) must be in RR.

The means f(0)=f(1)f(0)=f(1) and f(1)=f(0)f(1)=f(0) must be true for all ff.

But f(0)≠f(1)f(0) \neq f(1) always

Therefore, RR is not reflexive

If (f,g)∈R(f, g) \in R, then f(0)=g(1)f(0)=g(1) and f(1)=g(0)f(1)=g(0)

∵f(0)=g(1)⇒g(1)=f(0)\because f(0)=g(1) \Rightarrow g(1)=f(0)

and f(1)=g(0)⇒g(0)=f(1)f(1)=g(0) \Rightarrow g(0)=f(1)

RR is symmetric

If (f,g)∈R(f, g) \in R and (g,h)∈R(g, h) \in R, then f(0)=g(1)f(0)=g(1),

f(1)=g(0),g(0)=n(1)&g(1)=h(0)f(1)=g(0), g(0)=n(1) \& g(1)=h(0)

Since, f(0)=g(1)f(0)=g(1) and g(1)=h(0)g(1)=h(0), then f(0)f(0) is not necessarily equal to h(0)h(0).

Therefore, RR is not transitive.

∴\therefore \quad The relation RR is symmetric but not reflexive or transitive.

Answer key and solution verified before publishing.

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Exam
JEE Main 2025
Subject
Mathematics
Chapter
Sets and Relations
Topic
Types of Relations
Let A be the set of all function f: mathbb Z rightarrow mathbb Z and… | JEE Main 2025 PYQ with Solution · DhiX AI