VIT Engineering VIT Engineering Solved Paper-2011

  • question_answer
    If \[f(x)=\left\{ \begin{align} & \,\,\,\,\,\,\,\,\,{{x}^{2}},\,\,\,x\le 0 \\  & 2\,\sin x,\,\,\,x>0 \\ \end{align} \right.\,\,,\] then \[x=0\]is

    A)  point of minima

    B)  point of maxima

    C)  point of discontinuity

    D)  None of the above

    Correct Answer: A

    Solution :

    Given, \[f(x)=\left\{ \begin{align}   & \,\,\,\,\,\,\,\,\,{{x}^{2}},\,x\le 0 \\  & 2\sin x,\,x>0 \\ \end{align} \right.\] \[f(x)=\left\{ \begin{align}   & \,\,\,\,\,\,\,\,\,2x,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x\le 0 \\  & \text{non-differentiable,}\,\,x=0\,x=0\,\,\text{is} \\  & \,\,\,\,\,\,2\cos x,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x>0 \\ \end{align} \right.\] So, \[x=0\]is a critical point \[f({{0}^{-}})>0\]as well as \[f({{0}^{+}})>0\]and \[f(0)=0\] Hence, it is a point of minima.


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