10th Class Mathematics Polynomials Question Bank MCQs - Polynomials

  • question_answer
    If the square of difference of the zeroes of the quadratic polynomial \[{{x}^{2}}+px+45\] is equal to 144, then the value of p is:

    A) \[\pm 9\]

    B) \[\pm 12\]

    C) \[\pm 15\]

    D) \[\pm 18\]

    Correct Answer: D

    Solution :

    [d] Given that, \[f(x)={{x}^{2}}+px+45\]
    Then,    \[\alpha +\beta =\frac{-p}{1}=-p\] and \[\alpha \beta =\frac{45}{1}=45\]
    According to given condition,
                \[{{(\alpha -\beta )}^{2}}=144\]
    \[{{(\alpha +\beta )}^{2}}-4\alpha \beta =144\]
    \[{{(-p)}^{2}}-4(45)=144\]
    \[{{p}^{2}}=144+180\]
    \[{{p}^{2}}=324\Rightarrow p=\pm 18\]


You need to login to perform this action.
You will be redirected in 3 sec spinner