10th Class Mathematics Related to Competitive Exam Question Bank Algebra

  • question_answer
    For the equation\[|x{{|}^{2}}+|x|-6=0\]

    A)  there is only one root

    B)  the sum of the roots is 1

    C)  the sum of the roots is 0  

    D)  the product of the roots is 4

    Correct Answer: C

    Solution :

     Given   \[|x{{|}^{2}}+|x|-\,\,6=0\] Case I:                   \[x\ge 0\] Equation (i) reduces to\[{{x}^{2}}+x-6=0\] or            \[(x+3)(x-2)=0\] or            \[x=-3,\,\,2\] \[x=-3\] is impossible as\[x\ge 0\]. Therefore one root is\[x=2\]. Case II: \[x\le 0\] Equation (i) reduces to                 \[{{x}^{2}}-x-6=0\] or            \[(x-3)(x+2)=0\] or            \[x=3,\,\,-2\] \[x=3\] is impossible as\[x\le 0\]. Therefore one root is\[x=-2\]. Thus sum of the roots\[=0\].


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