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JEE Main & Advanced Mathematics Applications of Derivatives Question Bank Maxima and Minima

  • question_answer
    If the function \[f(x)={{x}^{4}}-62{{x}^{2}}+ax+9\]is maximum at \[x=1\], then the value of a is

    A)            120

    B)            ?120

    C)            52

    D)            128

    Correct Answer: A

    Solution :

               \[f(x)={{x}^{4}}-62{{x}^{2}}+ax+9\]            For maxima, \[f'(x)=4{{x}^{3}}-124x+a=0\]            At \[x=1,\,4{{(1)}^{3}}-124(1)+a=0\Rightarrow a=120\].


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