J & K CET Engineering J and K - CET Engineering Solved Paper-2015

  • question_answer
    Let \[X=\{a,b,c,d,e\}\] and \[R=\{(a,a),\,(b,b),\]\[(c,c),\,\,(a,b),\,\,(b,a)\}.\] Then, the relation R on X is

    A)  reflexive and symmetric

    B)  not reflexive, but symmetric

    C)  symmetric and transitive, but not reflexive

    D)  reflexive, but not transitive

    Correct Answer: C

    Solution :

    Given,  \[x=\{a,\,b\,c,\,d,e\}\] and \[R=\{(a,\,a),\,(b,b),(c,\,c),\,(a,b),\,(b,a)\}\]. For reflexive \[(x,x)\in R,\] since \[(d,\,d)\in /\,R\] Therefore, R is not reflexive. For symmetric \[(a,b)\in R\to (b,a)\in R\] Therefore, R is symmetric. For transitive Here, \[(a,b)\,\in R\] and \[(b,a)\in R\] \[\Rightarrow \] \[(a,a)\in R\] Therefore, R is transitive. Hence, R is symmetric and transitive, but not reflexive.


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