JEE Main & Advanced Mathematics Applications of Derivatives Question Bank Increasing and Decreasing Function

  • question_answer
    The function \[{{x}^{x}}\] is increasing, when   [MP PET 2003]

    A)            \[x>\frac{1}{e}\]

    B)            \[x<\frac{1}{e}\]

    C)            \[x<0\]

    D)            For all real x

    Correct Answer: A

    Solution :

               Let \[y={{x}^{x}}\] Þ \[\frac{dy}{dx}={{x}^{x}}(1+\log x)\]            For \[\frac{dy}{dx}>0\]; \[{{x}^{x}}(1+\log x)>0\]            Þ \[1+\log x>0\Rightarrow {{\log }_{e}}x>{{\log }_{e}}\frac{1}{e}\]            For this to be positive, x should be greater than \[\frac{1}{e}\].


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