MCQ
The relation $R$ in the set $\{1,2,3\}$ given by $R=\{(1,2)$, $(2,1),(1,1)\}$ is
  • A
    symmetric and transitive, but not reflexive
  • B
    reflexive and symmetric, but not transitive
  • C
    symmetric, but neither reflexive nor transitive
  • D
    an equivalence relation

Answer

Given, $R=\{(1,2),(2,1),(1,1)\}$ is a relation on set $\{1,2,3\}$
Reflexive : Clearly $(2,2),(3,3) \notin R$
$\therefore \quad R$ is not a reflexive relation.
Symmetric: Now, $(1,2) \in R$ and $(2,1) \in R \therefore R$ is symmetric.
Transitive: Now, $(2,1) \in R$ and $(1,2) \in R$ but $(2,2) \notin R$
$\therefore \quad R$ is not transitive relation.
$R$ is symmetric, but neither reflexive nor transitive.

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