JEE Main & Advanced Mathematics Equations and Inequalities Question Bank Self Evaluation Test - Linear Inequalities

  • question_answer
    The number of real roots of the equation \[\left| 2-\left| 1-\left| x \right| \right| \right|=1\] is

    A) 1

    B) 3

    C) 5

    D) 6

    Correct Answer: C

    Solution :

    [c] \[\left| 2-\left| 1-\left| x \right| \right| \right|=1\Rightarrow 2-\left| 1-\left| x \right| \right|=\pm 1\] \[\Rightarrow \left| 1-\left| x \right| \right|=1\,\,or\,\,3\] If \[\left| \left| 1- \right|x \right|=1\Rightarrow 1-\left| x \right|=\pm 1\Rightarrow \left| x \right|=0\,\,or\,\,2\] \[\Rightarrow x=0\,\,or\,\,\pm 2\] If \[\left| 1-\left| x \right| \right|=3\Rightarrow 1-\left| x \right|=\pm 3\Rightarrow \left| x \right|=-2or4\] \[\Rightarrow \left| x \right|=4\Rightarrow x=\pm 4\]          \[[\because \left| x \right|\ne -2]\] \[\therefore \] Solution set is\[\{-4,-2,0,2,4\}\], hence 5 real roots in all.


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