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JEE Main & Advanced Mathematics Complex Numbers and Quadratic Equations Question Bank Solution of quadratic equations and Nature of roots

  • question_answer
    If a root of the equation \[{{x}^{2}}+px+12=0\] is 4, while the roots of the equation \[{{x}^{2}}+px+q=0\] are same, then the value of \[q\]will be      [RPET 1991; AIEEE 2004]

    A) 4

    B) 4/49

    C) 49/4

    D) None of these

    Correct Answer: C

    Solution :

    Put\[x=4\]in\[{{x}^{2}}+px+12=0\], we get \[p=-7\] Now second equation \[{{x}^{2}}+px+q=0\] have equal roots. Therefore \[{{p}^{2}}=4q\,\,\,\Rightarrow \,\,\,q=\frac{49}{4}\]


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