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

  • question_answer
    The equation \[\left| |x-1|+a \right|=4\] can have real solution for x if 'a' belongs to the interval

    A) \[(-\infty ,+\infty )\]

    B) \[(-\infty ,4]\]

    C) \[(4,+\infty )\]

    D) \[[-4,4]\]

    Correct Answer: B

    Solution :

    [b] \[\left| \left| x-1 \right|+a \right|=4\Rightarrow \left| x-1 \right|+a=\pm 4\] \[\Rightarrow \left| x-1 \right|=-a\pm 4\] The above equation holds if \[-a+4\ge 0\] or \[-a-4\ge 0\] \[\Rightarrow a\le 4\]or \[a\le -4\Rightarrow a\in (-\infty ,4]\cup (-\infty ,-4]\] \[\Rightarrow a\in (-\infty ,4]\]


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