JEE Main & Advanced Mathematics Differentiation Question Bank Self Evaluation Test - Limits and Derivatives

  • question_answer
    If \[\underset{x\to a}{\mathop{\lim }}\,\left[ \frac{f(x)}{g(x)} \right]\]exist, then which one of the following correct?

    A) Both \[\underset{x\to a}{\mathop{\lim }}\,f(x)\] and \[\underset{x\to a}{\mathop{\lim }}\,g(x)\] must exist

    B) \[\underset{x\to a}{\mathop{\lim }}\,f(x)\] need not exist but \[\underset{x\to a}{\mathop{\lim }}\,g(x)\] must exist

    C) Both \[\underset{x\to a}{\mathop{\lim }}\,f(x)\] and \[\underset{x\to a}{\mathop{\lim }}\,g(x)\] need not exist

    D) None of these

    Correct Answer: D

    Solution :

    [d] \[f(x)=x,g(x)=\frac{1}{x}\] \[\underset{x\to 0}{\mathop{\lim }}\,f(x)=0,\underset{x\to 0}{\mathop{\lim }}\,g(x)=\] does not exist But \[\underset{x\to 0}{\mathop{\lim }}\,\left[ \frac{f(x)}{g(x)} \right]=\underset{x\to 0}{\mathop{\lim }}\,\left[ {{x}^{2}} \right]=0\] Hence, none of these is only true option.


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