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

  • question_answer
    The minimum value of \[{{e}^{(2{{x}^{2}}-2x+1){{\sin }^{2}}x}}\] is [Roorkee Qualifying 1998]

    A)            e

    B)            1/e

    C)            1

    D)            0

    Correct Answer: C

    Solution :

               Given \[y={{e}^{(2{{x}^{2}}-2x+1){{\sin }^{2}}x}}\]            For minima or maxima, \[\frac{dy}{dx}=0\]    \[\therefore {{e}^{(2{{x}^{2}}-2x+1){{\sin }^{2}}x}}[(4x-2){{\sin }^{2}}x+2(2{{x}^{2}}-2x+1)\sin x\cos x]=0\]            Þ \[[(4x-2){{\sin }^{2}}x+2(2{{x}^{2}}-2x+1)\sin x\cos x]=0\]            Þ \[2\sin x[(2x-1)\sin x+(2{{x}^{2}}-2x+1)\cos x]=0\]            Þ \[\sin x=0\]            \[\therefore y\]is minimum for \[\sin x=0\]            Thus minimum value of  \[y={{e}^{(2{{x}^{2}}-2x+1)(0)}}={{e}^{0}}=1\].


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