10th Class Mathematics Polynomials Question Bank MCQs - Polynomials

  • question_answer
    If a cubic polynomial with the sum of its zeroes, sum of the products and its zeroes taken two at a time and product of its zeroes as \[2,\,\,-5\] and \[-11\] respectively, then the cubic polynomial is:

    A) \[{{x}^{3}}+7x-6\]

    B) \[{{x}^{3}}+7x+6\]

    C) \[{{x}^{3}}-7x-6\]

    D) \[{{x}^{3}}-7x+6\]

    Correct Answer: D

    Solution :

    [d] Let \[\alpha ,\beta ,\gamma \] be the zeroes of the required polynomials
    \[\alpha +\beta +\gamma =0\]
    \[\alpha \beta +\beta \gamma +\alpha \gamma =-7\]
    \[\alpha \beta \gamma =-6\]
    Required cubic polynomial is
    \[k[{{x}^{3}}-(\alpha +\beta +\gamma ){{x}^{2}}+\]
    \[(\alpha \beta +\beta \gamma +\gamma \alpha )x-\alpha \beta \gamma ]\]
    where k is non-zero constant
    \[k[{{x}^{3}}+(0){{x}^{2}}+(-7)x-(-6)]={{x}^{3}}-7x+6\]
    [consider, \[k=1\]]


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