JEE Main & Advanced Mathematics Differentiation Question Bank Derivative at a point Standard Differentiation

  • question_answer
    If \[y={{\log }_{2}}[{{\log }_{2}}(x)]\], then \[\frac{dy}{dx}\]is equal to

    A)            \[\frac{{{\log }_{2}}e}{x{{\log }_{e}}x}\]

    B)            \[\frac{1}{{{\log }_{e}}x{{\log }_{e}}2}\]

    C)            \[\frac{1}{{{\log }_{e}}{{(2x)}^{x}}}\]

    D)            None of these

    Correct Answer: A

    Solution :

               \[y={{\log }_{2}}[{{\log }_{2}}(x)]={{\log }_{e}}({{\log }_{e}}x.{{\log }_{2}}e).{{\log }_{2}}e\]               \[=[{{\log }_{e}}{{\log }_{e}}x+{{\log }_{e}}({{\log }_{2}}e)]{{\log }_{2}}e\]            \[\therefore \frac{dy}{dx}={{\log }_{2}}e.\frac{1}{x{{\log }_{e}}x}\].


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