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

  • question_answer
    Solution of \[\left| 2x-3 \right|<\left| x+2 \right|\] is

    A) \[\left( -\infty ,\frac{1}{3} \right)\]

    B) \[\left( \frac{1}{3},5 \right)\]

    C) \[(5,\infty )\]

    D) \[\left( -\infty ,\frac{1}{3} \right)\cup (5,\infty )\]

    Correct Answer: B

    Solution :

    [b] \[\left| 2x-3 \right|<\left| x+2 \right|\]
    \[\Rightarrow -\left| x+2 \right|<2x-3<\left| x+2 \right|\]               ? (i)
    Case I: \[x+2\ge 0.\] Then by (i),
    \[-(x+2)<2x-3<x+2\]
    \[\Rightarrow -x-2<2x-3<x+2\]
    \[\Rightarrow 1<3x\,\,and\,\,x<5\Rightarrow \frac{1}{3}<x<5\]
    Case II: \[x+2<0.\] Then by (i),
    \[(x+2)<2x-3<-(x+2)\]
    \[\Rightarrow -(x+2)>2x-3>(x+2)\]
    \[\Rightarrow 1>3x\] and \[x>5\Rightarrow \frac{1}{3}\le x\] and \[x>5,\] not possible.


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