JEE Main & Advanced Mathematics Functions Question Bank Continuity

  • question_answer
    If\[f(x)=\left\{ \begin{align}   & {{e}^{1/x}},\ \text{when}\ x\ne 0 \\  & 0,\ \ \ \ \ \text{when}\ x=0 \\ \end{align} \right.\], then                   

    A)            \[\underset{x\to 0+}{\mathop{\lim }}\,f(x)=e\]

    B)            \[\underset{x\to 0+}{\mathop{\lim }}\,f(x)=0\]

    C)            \[f(x)\]is discontinuous at \[x=0\]

    D)            None of these

    Correct Answer: C

    Solution :

               \[f(0)=0\]                    \[\underset{x\to 0-}{\mathop{\lim }}\,f(x)=\underset{h\to 0}{\mathop{\lim }}\,\,{{e}^{-1/h}}=0\] and \[\underset{x\to 0+}{\mathop{\lim }}\,f(x)=\underset{h\to 0}{\mathop{\lim }}\,\,{{e}^{1/h}}=\infty \]            Hence function is discontinuous at \[x=0\].


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