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JEE Main & Advanced Mathematics Sets Question Bank Mock Test - Sets

  • question_answer
    If A=\[\{x|x\in \,N\,\]and \[({{x}^{2}}-4)\]\[({{x}^{2}}-5)\]=0} and B=\[\{x|x\in {{l}^{+}}\]and \[x(x-1)\]\[(x-2)\]=0} then \[(A\cup B)\]-\[(A\cap B)\]is

    A) {1, 2}

    B) {1}

    C) {2}                  

    D) \[\phi \]

    Correct Answer: B

    Solution :

    [b] \[({{x}^{2}}-4)({{x}^{2}}-5)=0\] \[\Rightarrow {{x}^{2}}-4=0\,\,or\,\,{{x}^{2}}-5=0\] \[\Rightarrow x=-2+2\,\,or\,\,x=-\sqrt{5},+\sqrt{5}\] \[So,\text{ }A=\{2\}\] \[x(x-1)(x-2)=0\] \[\Rightarrow x=0,1,2\] \[So,\text{ }B=\{1,2\}\] \[(A\cup B)-(A\cap B)=\{1,2\}-\{2\}=\{1\}\]


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