Equations And Inequalities Question 19

Question: The equation $ | |x-1|+a |=4 $ can have real solution for x if ‘a’ belongs to the interval

Options:

A) $ (-\infty ,+\infty ) $

B) $ (-\infty ,4] $

C) $ (4,+\infty ) $

D) $ [-4,4] $

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Answer:

Correct Answer: B

Solution:

  • [b] $ | | x-1 |+a |=4\Rightarrow | x-1 |+a=\pm 4 $
    $ \Rightarrow | x-1 |=-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] $