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

  • question_answer
    The number which exceeds its positive square root by 12 is

    A) 9

    B) 16

    C) 25

    D) None of these

    Correct Answer: B

    Solution :

    Let the required number is x So,  \[x=\sqrt{x}+12\,\,\,\Rightarrow x-12=\sqrt{x}\] Þ  \[{{x}^{2}}-25x+144=0\] Þ \[{{x}^{2}}-16x-9x+144=0\]\[\Rightarrow x=16\] Since \[x=9\] does not hold the condition. Trick: By inspection, since 16 exceeds its positive square root i.e.,4 by  12.


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