JEE Main & Advanced Mathematics Complex Numbers and Quadratic Equations Question Bank Relation between roots and coefficients

  • question_answer
    If \[\alpha \] and \[\beta \] are roots of \[a{{x}^{2}}+2bx+c=0\], then \[\sqrt{\frac{\alpha }{\beta }}+\sqrt{\frac{\beta }{\alpha }}\]is equal to [BIT Ranchi  1990]

    A) \[\frac{2b}{ac}\]

    B) \[\frac{2b}{\sqrt{ac}}\]

    C) \[-\frac{2b}{\sqrt{ac}}\]

    D) \[\frac{-b}{\sqrt{2}}\]

    Correct Answer: C

    Solution :

    Given equation is\[a{{x}^{2}}+2bx+c=0\]. So \[\alpha +\beta =-\frac{2b}{a}\]and \[\alpha \beta =\frac{c}{a}\] Now\[\sqrt{\left( \frac{\alpha }{\beta } \right)}+\sqrt{\left( \frac{\beta }{\alpha } \right)}=\frac{\alpha +\beta }{\sqrt{\alpha \beta }}=\frac{-2b/a}{\sqrt{c/a}}=-\frac{2b}{\sqrt{ac}}\].


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