JEE Main & Advanced Mathematics Limits, Continuity and Differentiability Question Bank Self Evaluation Test - Continuity and Differentiability

  • question_answer
    What is \[\underset{x\to 0}{\mathop{\lim }}\,\frac{\sqrt{1+x}-1}{x}\] equal to?

    A) 0

    B) \[\frac{1}{2}\]

    C) 1

    D) \[-\frac{1}{2}\]

    Correct Answer: B

    Solution :

    [b] \[\underset{x\to 0}{\mathop{\lim }}\,\frac{\sqrt{1+x}-1}{x}\] \[=\underset{x\to 0}{\mathop{\lim }}\,\frac{\sqrt{1+x}-1}{x}\times \frac{\sqrt{1+x}+1}{\sqrt{1+x}+1}\] \[=\underset{x\to 0}{\mathop{\lim }}\,\frac{1+x-1}{x\left[ \sqrt{1+x}+1 \right]}\] \[=\underset{x\to 0}{\mathop{\lim }}\,\frac{1}{\sqrt{1+x}+1}=\frac{1}{\sqrt{1+0}+1}=\frac{1}{2}\]


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