10th Class Mathematics Polynomials Question Bank MCQs - Polynomials

  • question_answer
    If sum and product of zeroes of quadratic polynomial are, respectively 8 and 12, then their zeroes are

    A) 2 and 6

    B) 3 and 4

    C) 2 and 8

    D) 2 and 5

    Correct Answer: A

    Solution :

    Let the zeroes of the quadratic polynomial   are \[\alpha \] and \[\beta \]
    \[\alpha +\beta =8\]                                           … (i)
    And \[\alpha \,.\,\beta =12\]                                            … (ii)
    Substitute value of \[\beta =8-\alpha \]in Eq. (ii)
    \[\alpha \left( 8-\alpha  \right)=12\]
    \[{{\alpha }^{2}}-8\alpha +12=0\]
    \[{{\alpha }^{2}}-6\alpha -2\alpha +12=0\]
    \[\alpha \left( \alpha -6 \right)-2\left( \alpha -6 \right)=0\]
    \[\alpha =6,\,\alpha =2\]
    If \[\alpha =6\], then \[\beta =2\]
    If \[\alpha =2\], then \[\beta =6\]
    Hence, the two zeroes are 2 and 6.


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