JCECE Engineering JCECE Engineering Solved Paper-2008

  • question_answer
    The domain of the function\[{{\sin }^{-1}}\left( {{\log }_{2}}\frac{{{x}^{2}}}{2} \right)\]is

    A) \[[-1,\,\,2]-\{0\}\]                           

    B) \[[-2,\,\,2]-(-1,\,\,1)\]

    C) \[[-2,\,\,2]-\{0\}\]                           

    D)  \[[1,\,\,2]\]

    Correct Answer: B

    Solution :

    Key Idea The domain of\[{{\sin }^{-1}}x\]is\[[-1,\,\,1]\]. Since, domain of \[{{\sin }^{-1}}x\]is\[[-1,\,\,1]\]. \[\therefore \]  \[{{\sin }^{-1}}\left[ {{\log }_{2}}\frac{{{x}^{2}}}{2} \right]\] \[\Rightarrow \]               \[-1\le {{\log }_{2}}\frac{{{x}^{2}}}{2}\le 1\] \[\Rightarrow \]               \[{{2}^{-1}}\le \frac{{{x}^{2}}}{2}\le 2\] \[\Rightarrow \]               \[\frac{1}{2}\le \frac{{{x}^{2}}}{2}\le 2\] \[\Rightarrow \]               \[1\le {{x}^{2}}\le 4\] \[\Rightarrow \]               \[|x|\le 2\]and\[|x|\,\,\ge 1\] \[\Rightarrow \]               \[x\in \{[-2,\,\,2]-(-1,\,\,1)\}\].


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