JEE Main & Advanced Sample Paper JEE Main - Mock Test - 11

  • question_answer
    The value of \[\underset{x\to 1}{\mathop{\lim }}\,{{\left( \frac{4}{\pi }{{\tan }^{-1}}x \right)}^{\frac{1}{({{x}^{2}}-1)}}}\] is equal to

    A) \[{{e}^{\frac{1}{\pi }}}\]                    

    B) \[{{e}^{-\frac{1}{\pi }}}\]

    C) \[{{e}^{\frac{2}{\pi }}}\]                   

    D) \[{{e}^{-\frac{2}{\pi }}}\]

    Correct Answer: A

    Solution :

    [a] \[L=\underset{x\to 1}{\mathop{\lim }}\,{{\left( \frac{4}{\pi }{{\tan }^{-1}}x \right)}^{\frac{1}{({{x}^{2}}-\,1)}}}={{e}^{\underset{x\to 1}{\mathop{\lim }}\,\,\frac{1}{{{x}^{2}}-\,1}\left( \frac{4}{\pi }{{\tan }^{-1}}x-\,t \right)}}\] Now, \[\underset{x\to 1}{\mathop{\lim }}\,\frac{\left( \frac{4}{\pi }{{\tan }^{-1}}x-1 \right)}{{{x}^{2}}-1}=\underset{x\to 1}{\mathop{\lim }}\,\frac{\frac{4}{\pi }\frac{1}{1+{{x}^{2}}}}{2x}=\frac{1}{\pi }\] \[\therefore \,\,\,L={{e}^{\frac{1}{\pi }}}\]


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