JEE Main & Advanced Mathematics Sets Question Bank Self Evaluation Test - Sets

  • question_answer
    A, B, C and D are four sets such that \[A\cap B=C\cap D=\phi .\] Consider the following:
    1. \[A\cup B\] and \[B\cup D\] are always disjoint.
    2. \[A\cap C\] and \[B\cap D\] are always disjoint.
    Which of the above statements is/are correct?

    A) 1 Only

    B)                   2 only

    C) Both 1 and 2

    D)        neither 1 nor 2s

    Correct Answer: B

    Solution :

    [b]Let \[A=\{1,2\}\]
    \[B=\{3,4,0\}\]
    \[C=\{5,6,0\}\]
    \[D=\{7,8\}\]
    Such that \[(A\cap B)=(C\cap D)=\phi \]
    \[\Rightarrow (A\cup C)=\{1,2,5,6,0\}\]
    \[\Rightarrow (B\cup D)=\{3,4,7,8,0\}\]
    \[\Rightarrow (A\cup C)\cap (B\cup D)=\{0\}\]
    So \[(A\cup C)\] and \[(B\cup D)\] are not always disjoint
    \[\Rightarrow (A\cap C)=\phi \] and \[(B\cap D)=\phi \]
    So \[(A\cap C)\] and \[(B\cap D)\]are always disjoint.


You need to login to perform this action.
You will be redirected in 3 sec spinner