JEE Main & Advanced Mathematics Functions Question Bank Limits

  • question_answer
    \[\underset{x\to 0}{\mathop{\lim }}\,\,\frac{\text{ln}\,(\cos x)}{{{x}^{2}}}\] is equal to [AMU 2000]

    A)                 0

    B)                 1

    C)                 \[\frac{1}{2}\]

    D)                 \[-\frac{1}{2}\]

    Correct Answer: D

    Solution :

                       Applying L-Hospital?s rule,                                 \[\underset{x\to 0}{\mathop{\lim }}\,\frac{\ln (\cos x)}{{{x}^{2}}}\]\[=\underset{x\to 0}{\mathop{\lim }}\,\frac{-\tan x}{2x}\]\[=\underset{x\to 0}{\mathop{\lim }}\,\frac{-{{\sec }^{2}}x}{2}=\frac{-1}{2}\].


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