Question:

Let R be the relation in the set N given by R = {(a, b): a = b − 2, b > 6}. Choose the correct answer. (A) (2, 4) ∈ R (B) (3, 8) ∈R (C) (6, 8) ∈R (D) (8, 7) ∈ R

Updated On: Aug 19, 2023
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Solution and Explanation

R = {(a, b): a = b − 2, b > 6 }
Now, since b > 6, (2, 4) ∉ R
Also, as 3 ≠ 8 − 2, (3, 8) ∉ R
And, as 8 ≠ 7 − 2
∴ (8, 7) ∉ R
Now, consider (6, 8).
We have 8 > 6 and also, 6 = 8 − 2.
∴ (6, 8) ∈ R

The correct answer is C. 

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Concepts Used:

Types of Relation

TYPES OF RELATION

Empty Relation

Relation is said to be empty relation if no element of set X is related or mapped to any element of X i.e, R = Φ.

Universal Relation

A relation R in a set, say A is a universal relation if each element of A is related to every element of A.

R = A × A.

Identity Relation

Every element of set A is related to itself only then the relation is identity relation.

Inverse Relation

Let R be a relation from set A to set B i.e., R ∈ A × B. The relation R-1 is said to be an Inverse relation if R-1 from set B to A is denoted by R-1

Reflexive Relation

If every element of set A maps to itself, the relation is Reflexive Relation. For every a ∈ A, (a, a) ∈ R.

Symmetric Relation

A relation R is said to be symmetric if (a, b) ∈ R then (b, a) ∈ R, for all a & b ∈ A.

Transitive Relation

A relation is said to be transitive if, (a, b) ∈ R, (b, c) ∈ R, then (a, c) ∈ R, for all a, b, c ∈ A

Equivalence Relation

A relation is said to be equivalence if and only if it is Reflexive, Symmetric, and Transitive.