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10th Class Mathematics Polynomials Question Bank MCQs - Polynomials

  • question_answer
    If  the   zeroes   of  the   quadratic   polynomial \[{{x}^{2}}+(a+1)x+b\] are \[4\] and \[-3,\] then \[a-b\] is:

    A) 12

    B) \[10\]

    C) \[7\]

    D) \[1\]

    Correct Answer: B

    Solution :

    [b] It is given that 4 and \[-3\] are the zeroes of the polynomial
    \[{{x}^{2}}+(a+1)x+b.\]
    \[\therefore \]    Sum of zeroes \[=-\frac{(a+1)}{1}=-a-1\]
    \[\Rightarrow \,\,4+(-3)=-a-1\Rightarrow 1=-a-1\Rightarrow a=-2\]
    And product of zeroes = b
    \[\Rightarrow \,\,\,\,\,\,\,\,(4)\,(-3)=b\Rightarrow \,=-12\]
    \[\therefore \,\,\,\,\,\,\,a-b=-2\,(-12)=-2+12=10\]


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