JEE Main & Advanced Sample Paper JEE Main Sample Paper-15

  • question_answer
    Let \[f(x)={{x}^{3}}-{{x}^{2}}+x+1\] and\[g(x)=\left\{ \begin{align}   & \max \{f(t);0\le t\le x\};0\le x\le 1 \\  & (3-x)\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,1<x\le 2 \\ \end{align} \right.\]then

    A)  \[g(x)\] is continuous and derivable in (0,2)

    B)  \[g(x)\] is discontinuous at finite number of points in (0,2)

    C)  \[g(x)\] is non-derivable at 2 points

    D)  \[g(x)\] is continuous but non-derivable at one point

    Correct Answer: D

    Solution :

    \[g(g)=\left\{ \begin{align}   & {{x}^{3}}-{{x}^{2}}+x+1\,;\,0\le x\le 1 \\  & 3-x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,;\,1<x\le 2 \\ \end{align} \right.\] Now, \[g(x)\] is continuous at \[x=1\] but non-derivative at\[x=1\].


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