JEE Main & Advanced Mathematics Functions Question Bank Functions

  • question_answer
    The domain of the function \[\sqrt{\log ({{x}^{2}}-6x+6)}\] is            [Roorkee 1999; MP PET 2002]

    A)            \[(-\infty ,\ \infty )\]                    

    B)            \[(-\infty ,\ 3-\sqrt{3})\cup (3+\sqrt{3},\ \infty )\]

    C)            \[(-\infty ,\ 1]\cup [5,\ \infty )\]                                      

    D)            \[[0,\ \infty )\]

    Correct Answer: C

    Solution :

               The function \[f(x)=\sqrt{\log ({{x}^{2}}-6x+6)}\] is defined when \[\log ({{x}^{2}}-6x+6)\ge 0\]            Þ \[{{x}^{2}}-6x+6\ge 1\]   Þ \[(x-5)(x-1)\ge 0\]                    This inequality holds if \[x\le 1\] or \[x\ge 5\]. Hence, the domain of the function will be \[(-\infty ,\,1]\cup [5,\,\infty )\].


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