JEE Main & Advanced Mathematics Functions Question Bank Limits

  • question_answer
    \[\underset{x\to 0}{\mathop{\lim }}\,\frac{\sqrt{\frac{1}{2}(1-\cos 2x)}}{x}=\]  [IIT 1991; AIEEE 2002; RPET 2001, 02]

    A)                 1

    B)                 ?1

    C)                 0

    D)                 None of these

    Correct Answer: D

    Solution :

                       \[\underset{x\to 0}{\mathop{\lim }}\,\,\frac{\sqrt{\tfrac{1}{2}(1-\cos 2x)}}{x}=\underset{x\to 0}{\mathop{\lim }}\,\,\frac{|\,\,\sin x\,\,|}{x}\]            So, \[\underset{x\to 0+}{\mathop{\lim }}\,\,\frac{|\,\sin x\,|}{x}=1\] and \[\underset{x\to 0-}{\mathop{\lim }}\,\,\frac{|\,\sin x\,|}{x}=-1\]                                 Hence limit does not exist.


You need to login to perform this action.
You will be redirected in 3 sec spinner