10th Class Mathematics Polynomials Question Bank MCQs - Polynomials

  • question_answer
    If one zero of the polynomial\[3{{x}^{2}}-8x+2k+1\]is seven times the other, then the value of k is

    A) \[\frac{2}{5}\]

    B) \[\frac{2}{3}\]

    C) \[\frac{2}{7}\]

    D) \[\frac{3}{2}\]

    Correct Answer: B

    Solution :

    Let the zeroes of the polynomial
    \[3{{x}^{2}}-8x+2k+1\] be \[\alpha ,\,\,\beta \]
    \[\Rightarrow \,\,\,\alpha +\beta =\frac{8}{3}\]
    We have, \[\alpha =7\beta \]
    \[\Rightarrow \,\,\,\,\,7\beta +\beta =\frac{8}{3}\]
    \[\Rightarrow \,\,\,\,\,\,\,\,\beta =\frac{1}{3}\]
    \[\Rightarrow \,\,\,\,\,\,\,\,\,\alpha =\frac{7}{3}\] and \[\beta =\frac{1}{3}\]
    \[\alpha \,.\,\beta =\frac{2k+1}{3}\]
    \[2k=\frac{4}{3}\,\,\Rightarrow \,k=\frac{2}{3}\]


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