RAJASTHAN ­ PET Rajasthan PET Solved Paper-2004

  • question_answer
    The point of inflexion on the curve\[y={{x}^{5/3}}\] will be

    A)  (0, 0)              

    B)  (1, 0)

    C)  (0, 1)              

    D)  does not exist

    Correct Answer: D

    Solution :

     Given,        \[y={{x}^{5/3}}\] \[\Rightarrow \] \[\frac{dy}{dx}=\frac{5}{3}{{x}^{2/3}}\] For the point of inflexion, \[\frac{dy}{dx}=0\] \[\Rightarrow \] \[\frac{5}{3}{{x}^{2/3}}=0\] \[\Rightarrow \] \[x=0\] \[\Rightarrow \] \[y=0\] So, point is (0, 0) Now,       \[\frac{{{d}^{2}}y}{d{{x}^{2}}}=\frac{5}{3}.\frac{2}{3}{{x}^{-1/3}}\] \[{{\left( \frac{{{d}^{2}}y}{d{{x}^{2}}} \right)}_{x=0}}=0\] Hence, point of inflexion does not exist.


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