JEE Main & Advanced Sample Paper JEE Main Sample Paper-47

  • question_answer
    \[\underset{x\to 0}{\mathop{\lim }}\,\,\frac{\tan ([-{{\pi }^{2}}]{{x}^{2}})-\tan \,([-{{\pi }^{2}}]){{x}^{2}}}{{{\sin }^{2}}x}\] is equal to, where \[[\cdot ]\] denotes the greatest integers functions,

    A)  0                                

    B)  1

    C)  \[\tan \,\,10-10\]                     

    D)  \[\infty \]

    Correct Answer: C

    Solution :

     \[\because \]    \[\pi =3,\,\,14\] \[{{\pi }^{2}}=9.86\] \[[-{{\pi }^{2}}]=[-9.86]=-10\] Then, \[\underset{x\to 0}{\mathop{\lim }}\,\,\frac{\tan \,(-10{{x}^{2}})\,-{{x}^{2}}\,\tan \,(-10)}{{{\sin }^{2}}x}\] \[\Rightarrow \] \[\underset{x\to 0}{\mathop{\lim }}\,\,\frac{\frac{-\tan \,10\,{{x}^{2}}}{10{{x}^{2}}}\times \frac{10{{x}^{2}}}{{{x}^{2}}}+\frac{{{x}^{2}}\,\tan \,10}{{{x}^{2}}}}{\frac{{{\sin }^{2}}x}{{{x}^{2}}}}\] \[\left( \begin{align}   & \because \,\underset{\theta \to 0}{\mathop{\lim }}\,\,\frac{\sin \theta }{\theta }=1 \\  & \underset{\theta \to 0}{\mathop{\lim }}\,\,\frac{\tan \,\theta }{\theta }=1 \\ \end{align} \right)\] \[=\frac{-10+\tan \,10}{1}\] \[=\tan 10-10\]


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