JEE Main & Advanced Sample Paper JEE Main - Mock Test - 23

  • question_answer
    \[\underset{x\to 0}{\mathop{\lim }}\,{{\left( \frac{1+5{{x}^{2}}}{1+3{{x}^{2}}} \right)}^{1/{{x}^{2}}}}=\]

    A) \[{{e}^{2}}\]              

    B) \[{{e}^{3}}\]

    C) \[{{e}^{5}}\]              

    D)  e

    Correct Answer: A

    Solution :

    [a]:\[\underset{x\to 0}{\mathop{\lim }}\,{{\left( \frac{1+5{{x}^{2}}}{1+3{{x}^{2}}} \right)}^{1/{{x}^{2}}}}({{1}^{\infty }}form)\] \[=\exp \underset{x\to 0}{\mathop{\lim }}\,\left( \frac{1+5{{x}^{2}}}{1+3{{x}^{2}}}-1 \right)\left( \frac{1}{{{x}^{2}}} \right)\] \[=\exp \underset{x\to 0}{\mathop{\lim }}\,\left( \frac{2}{1+3{{x}^{2}}} \right)={{e}^{2}}.\]


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