JAMIA MILLIA ISLAMIA Jamia Millia Islamia Solved Paper-2013

  • question_answer
        If the roots of the equation\[a{{x}^{2}}+bx+c=0\] are real and distinct, then

    A)  both roots are greater than \[\frac{-b}{2a}\]

    B)  both roots are less than\[\frac{-b}{2a}\]

    C)  one of the roots exceeds\[\frac{-b}{2a}\]

    D)  None of the above

    Correct Answer: C

    Solution :

                    Since, the roots of the given equation are \[\alpha =\frac{-b-\sqrt{{{b}^{2}}-4ac}}{2a}\] and       \[\beta =\frac{-b+\sqrt{{{b}^{2}}-4ac}}{2a}\] Since,\[\alpha \]and\[\beta \]are real and distinct. Then,       \[{{b}^{2}}-4ac>0\] Now, if\[a>0,\]then \[\beta >\frac{-b}{2a}\] and if \[a<0,\]then \[\alpha <\frac{-b}{2a}\] Thus, one of the roots exceeds\[\frac{-b}{2a}\]


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