JEE Main & Advanced Mathematics Functions Question Bank Limits

  • question_answer
    \[\underset{x\to \infty }{\mathop{\lim }}\,\left[ \sqrt{x+\sqrt{x+\sqrt{x}}}-\sqrt{x} \right]\]is equal to

    A)                 0

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

    C)                 \[\frac{1}{p}-\frac{1}{p-1}\]

    D)                 \[{{e}^{4}}\]

    Correct Answer: B

    Solution :

                       \[\underset{x\to \infty }{\mathop{\lim }}\,\,\left[ \sqrt{x+\sqrt{x+\sqrt{x}}}-\sqrt{x} \right]=\underset{x\to \infty }{\mathop{\lim }}\,\frac{x+\sqrt{x+\sqrt{x}}-x}{\sqrt{x+\sqrt{x+\sqrt{x}}}+\sqrt{x}}\]                                 \[=\underset{x\to \infty }{\mathop{\lim }}\,\frac{\sqrt{x+\sqrt{x}}}{\sqrt{x+\sqrt{x+\sqrt{x}}}+\sqrt{x}}=\underset{x\to \infty }{\mathop{\lim }}\,\,\frac{\sqrt{1+{{x}^{-1/2}}}}{\sqrt{1+\sqrt{{{x}^{-1}}+{{x}^{-3/2}}}}+1}=\frac{1}{2}\].


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