10th Class Mathematics Polynomials Question Bank MCQs - Polynomials

  • question_answer
    If \[\alpha ,\beta ,\gamma \] are the zeroes of the polynomial \[{{x}^{3}}+p{{x}^{2}}+qx+r,\] then \[\left( \frac{1}{\alpha \beta }+\frac{1}{\beta \gamma }+\frac{1}{\gamma \alpha } \right)=\]

    A) \[\frac{p}{r}\]

    B) \[-\frac{p}{r}\]

    C) \[\frac{q}{r}\]

    D) \[-\frac{q}{r}\]

    Correct Answer: A

    Solution :

    [a] Since \[\alpha ,\beta ,\gamma \] are the zeroes of the polynomial
    \[{{x}^{3}}+p{{x}^{2}}+qx+r.\]
                \[\therefore \,\,\,\,\,\,\,\,\,\alpha +\beta +\gamma =-p,\,\alpha \beta \gamma =-r\]
    Now,   \[\frac{1}{\alpha \beta }+\frac{1}{\beta \gamma }+\frac{1}{\gamma \alpha }=\frac{\alpha +\beta +\gamma }{\alpha \beta \gamma }=\frac{-p}{-r}=\frac{p}{r}\]


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