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

  • question_answer
    The number of integral roots of the equation\[\left| x-1 \right|+\left| x+2 \right|-\left| x-3 \right|=4\] is

    A) 0

    B) 1

    C) 2

    D) 4

    Correct Answer: C

    Solution :

    [c] \[\left| x-1 \right|+\left| x+2 \right|-\left| x-3 \right|=4,\]has three absolute value expressions, thus we divide the problem into four intervals:
    (i) If \[x<-2\] then
    \[-(x-1)-(x+2)+(x-3)=4\Rightarrow x=-8\]
    (ii) If \[-2\le x<1,\] then
    \[-(x-1)+(x+2)+(x-3)=4\]
    \[\Rightarrow \,\,\,\,x=4\notin [-2,\,\,\,1),\] hence rejected
    (iii) If \[1\le x<3,\] then
    \[(x-1)+(x+2)+(x-3)=4\Rightarrow x=2\]
    (iv) If \[x\ge 3,\] then
    \[(x-1)+(x+2)-(x-3)=4\Rightarrow x=0\notin [3,\infty ),\]
    Hence rejected
    \[\therefore \] Solution set is \[\{-8,2\}\] and both are integers


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