English

The Relation R = {(1, 1), (2, 2), (3, 3)} on the Set {1, 2, 3} is (A) Symmetric Only (B) Reflexive Only (C) an Equivalence Relation (D) Transitive Only

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Question

The relation R = {(1, 1), (2, 2), (3, 3)} on the set {1, 2, 3} is ___________________ .

Options

  • symmetric only

  • reflexive only

  • an equivalence relation

  • transitive only

MCQ
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Solution

an equivalence relation

R={ (a, b) : a = b and a, b ∈ A }

Reflexivity : Let a ∈ A 

Here,

a = a 

⇒ (a, a) ∈ R for all a ∈ A

So, R is reflexive on A

Symmetry : Let a, b ∈ A such that (a, b) ∈ R. Then,

(a, b) ∈ R

⇒ a = b

⇒ b = a

⇒ (b, a) ∈ R for all a ∈ A

So, R is symmetric on A.

Transitive : Let a, b, c ∈ A such that (a, b) ∈ R and (b, c) ∈ R.

Then, (a, b) ∈ R ⇒ a = b and (b, c) ∈ R ⇒ b = c

⇒ a = c 

⇒ (a, c) ∈ R for all a ∈ A

So, R is transitive on A.

Hence, R is an equivalence relation on A.

 

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Chapter 1: Relations - Exercise 1.4 [Page 32]

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R.D. Sharma Mathematics Volume 1 and 2 [English] Class 12
Chapter 1 Relations
Exercise 1.4 | Q 24 | Page 32

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