Target Exam

CUET

Subject

-- Mathematics - Section A

Chapter

Relations and Functions

Question:

Let R be the relation on the set {1, 2, 3, 4} defined by R = {(1, 2), (2, 1), (2, 2), (3, 3), (4, 4), (1, 4), (4, 1)}. Then R is:

Options:

Reflexive but not symmetric

Symmetric but not transitive

Transitive but not reflexive

Equivalence Relation

Correct Answer:

Symmetric but not transitive

Explanation:

Given set $A=\{1,2,3,4\}$

$R=\{(1,2),(2,1),(2,2),(3,3),(4,4),(1,4),(4,1)\}$

Reflexive:

For reflexive relation, $(1,1),(2,2),(3,3),(4,4)$ must be present.

$(1,1)$ is missing.

Hence, $R$ is not reflexive.

Symmetric:

If $(a,b)\in R$ then $(b,a)\in R$.

$(1,2)$ and $(2,1)$ ✓

$(1,4)$ and $(4,1)$ ✓

Thus $R$ is symmetric.

Transitive:

$(1,2)$ and $(2,1)$ imply $(1,1)$ which is not in $R$.

Hence $R$ is not transitive.

final answer: The relation is symmetric but neither reflexive nor transitive.