JEE Main & Advanced Mathematics Differentiation Question Bank Self Evaluation Test - Limits and Derivatives

  • question_answer
    The value of \[\underset{x\to 0}{\mathop{\lim }}\,{{\log }_{e}}{{(sinx)}^{\tan x}}\] is

    A) 1

    B) -1

    C) 0

    D) None of these

    Correct Answer: C

    Solution :

    [c] \[\underset{x\to 0}{\mathop{\lim }}\,{{\log }_{e}}{{(sinx)}^{\tan x}}=\underset{x\to 0}{\mathop{\lim }}\,\tan x.{{\log }_{e}}\sin x\]                                     \[(0\cdot \infty \,\,form)\] \[\underset{x\to 0}{\mathop{\lim }}\,\frac{{{\log }_{e}}\sin x}{\cot x}\left( \frac{\infty }{\infty }form \right)\] \[=\underset{x\to 0}{\mathop{\lim }}\,\frac{\cot x}{-\cos e{{c}^{2}}x}\] [Using L?Hospital?s rule] \[=\underset{x\to 0}{\mathop{\lim }}\,(-cosx.sinx)=0.\]


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