JEE Main & Advanced Mathematics Functions Question Bank Continuity

  • question_answer
    If \[f(x)=\left\{ \begin{align}   & {{2}^{1/x}},\text{for}\,x\ne 0 \\  & \,\,\,\,\,\,\,3,\text{for}\,x=\text{0} \\ \end{align} \right.\], then

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

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

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

    D)  None of these

    Correct Answer: D

    Solution :

               \[\underset{x\to 0+}{\mathop{\lim }}\,f(x)=\underset{h\to 0}{\mathop{\lim }}\,\,\,{{2}^{1/h}}=\infty \]            \[\underset{x\to 0-}{\mathop{\lim }}\,f(x)=\underset{h\to 0}{\mathop{\lim }}\,\,\,{{2}^{-1/h}}=\underset{h\to 0}{\mathop{\lim }}\,\,\frac{1}{{{2}^{1/h}}}=0\].


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