JEE Main & Advanced Mathematics Functions Question Bank Limits

  • question_answer
    \[\underset{x\to \infty }{\mathop{\lim }}\,\frac{\sqrt{{{x}^{2}}+{{a}^{2}}}-\sqrt{{{x}^{2}}+{{b}^{2}}}}{\sqrt{{{x}^{2}}+{{c}^{2}}}-\sqrt{{{x}^{2}}+{{d}^{2}}}}=\]

    A)                 \[\frac{{{a}^{2}}-{{b}^{2}}}{{{c}^{2}}-{{d}^{2}}}\]

    B)                 \[\frac{{{a}^{2}}+{{b}^{2}}}{{{c}^{2}}-{{d}^{2}}}\]

    C)                 \[\frac{{{a}^{2}}+{{b}^{2}}}{{{c}^{2}}+{{d}^{2}}}\]

    D)                 None of these

    Correct Answer: A

    Solution :

                    \[\underset{x\to \infty }{\mathop{\lim }}\,\,\frac{({{a}^{2}}-{{b}^{2}})}{({{c}^{2}}-{{d}^{2}})}\,\frac{\left[ \sqrt{1+\frac{{{c}^{2}}}{{{x}^{2}}}}+\sqrt{1+\frac{{{d}^{2}}}{{{x}^{2}}}} \right]}{\left[ \sqrt{1+\frac{{{a}^{2}}}{{{x}^{2}}}}+\sqrt{1+\frac{{{b}^{2}}}{{{x}^{2}}}} \right]}=\frac{{{a}^{2}}-{{b}^{2}}}{{{c}^{2}}-{{d}^{2}}}.\]


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