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

  • question_answer
    The value of the function \[(x-1){{(x-2)}^{2}}\] at its maxima is

    A)            1

    B)            2

    C)            0

    D)            \[\frac{4}{27}\]

    Correct Answer: D

    Solution :

               Given \[f(x)=(x-1){{(x-2)}^{2}}\]                    \[f(x)=(x-1)({{x}^{2}}+4-4x)\]; \[f(x)=({{x}^{3}}-5{{x}^{2}}+8x-4)\]                    Now \[f'(x)=3{{x}^{2}}-10x+8\], \[f'(x)=0\]                    Þ \[3{{x}^{2}}-10x+8=0\]Þ \[(3x-4)(x-2)=0\]Þ \[x=\frac{4}{3}\], 2                    Now   \[{f}''(x)=6x-10\]                                 \[{f}''(4/3)=6\times 4/3-10<0\]                                 \[{f}''(2)=12-10>0\]                    Hence at \[x=\frac{4}{3}\] the function will occupy maximum value.                    \[\therefore \] Maximum value =\[f(4/3)=4/27\].


You need to login to perform this action.
You will be redirected in 3 sec spinner