10th Class Mathematics Polynomials Question Bank Polynomials

  • question_answer
    If sum of all zeros of the polynomial \[5{{x}^{2}}-(3+k)x+7\] is zero, then zeroes of the polynomial \[2{{x}^{2}}-2(k+11)x+30\] are

    A)  3, 5     

    B)         7, 9                

    C)         3, 6                

    D)         2, 5                            

    Correct Answer: A

    Solution :

            Sum of zeroes of polynomial \[5{{x}^{2}}-(3+k)x+7\] is \[\frac{-[-(3+k)]}{5}\] i.e., \[\frac{3+k}{5}\] According to question, \[\frac{3+k}{5}=0\Rightarrow k=-3\] Now, \[2{{x}^{2}}-2(k+11)x+30\] becomes \[2{{x}^{2}}-16x+30.\] i.e., \[2{{x}^{2}}-16x+30=0\]  or \[{{x}^{2}}-8x+15=0\] \[\Rightarrow \]            \[x=3,5\] Hence, zeroes of polynomial \[2{{x}^{2}}-16x+30\] are 3,5.


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