JEE Main & Advanced Sample Paper JEE Main Sample Paper-41

  • question_answer
    The   critical   points   of   the   function\[f(x)={{(x-2)}^{2/3}}(2x+1)\]

    A)  1 and 2                      

    B)  1 and -1/2

    C)  -1 and 2                     

    D)  1

    Correct Answer: A

    Solution :

    Given that, \[f(x)={{(x-2)}^{2/3}}(2x+1)\] \[\Rightarrow \]\[f'(x)=\frac{2}{3}{{(x-2)}^{-1/3}}(2x+1)+2{{(x-2)}^{2/3}}\] Clearly, f' (x) is not defined at x = 2, So x = 2 is a critical point and for another critical point, Put f'(x) = 0. \[\therefore \]\[\frac{2}{3}{{(x-2)}^{-1/3}}(2x+1)+2{{(x-2)}^{2/3}}=0\] \[\Rightarrow \]\[2x+1=-3(x-2)\]\[\Rightarrow \]\[x=1\] Hence, 1 and 2 are two critical points of f(x).


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