JEE Main & Advanced Mathematics Functions Question Bank Self Evaluation Test - Relation and Functions-II

  • question_answer
    Let n be a fixed positive integer. Define a relation R in the set Z of integers by aRb if and only if \[\frac{n}{a-b}.\]The relation R is

    A) reflexive

    B) Symmetric

    C) Transitive

    D) An equivalence relation

    Correct Answer: D

    Solution :

    [d] we have, \[R=\{(a,b):n/(a-b):a,b\in Z\}\] Let \[z\in Z.\therefore a-a=0=n\times 0ie.n/(a-a)\] \[\therefore (a,a)\in R\] i.e. R is reflexive. Let \[(a,b)\in R.\]             \[\therefore \,n/(a-b)\] \[\Rightarrow n/-(a-b)\Rightarrow n/(b-a)\Rightarrow (b,a)\in R\] \[\therefore \] R is symmetric. Let \[(a,b),(b,c)\in R\therefore n/(a-b),n/(b-c)\] \[\Rightarrow n/(a-b)+(b-c)\Rightarrow n/a-c\Rightarrow (a,c)\in R\] \[\therefore \] R is transitive. \[\therefore \] R an equivalence relation.


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