JEE Main & Advanced JEE Main Paper (Held On 11-Jan-2019 Evening)

  • question_answer
    All x satisfying the inequality\[{{(co{{t}^{-1}}x)}^{2}}-7(co{{t}^{-1}}x)+10>0,\] lie in the interval [JEE  Main Online Paper (Held on 11-jan-2019 Evening)]

    A) \[(-\infty ,\cot 5)\cup (cot4,cot2)\]

    B) \[(\cot 5,cot4)\]

    C) \[(-\infty ,\cot 5)\cup (cot2,\infty )\]

    D) \[(cot2,\infty )\]

    Correct Answer: D

    Solution :

    Here,\[{{({{\cot }^{-1}}x)}^{2}}-7({{\cot }^{-1}}x)+10>0\] \[\Rightarrow \]\[(co{{t}^{-1}}x-5)(co{{t}^{-1}}x-2)>0\] \[\Rightarrow \]\[(co{{t}^{-1}}x>5or\,co{{t}^{-1}}x<2\] \[\Rightarrow \]\[x<\cot 5\,or\,x>\cot 2\] Since, \[x<\cot \,5\]does not satisfy the given inequality. \[\therefore \]\[x\in (cot2,\infty )\]


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