RAJASTHAN ­ PET Rajasthan PET Solved Paper-2007

  • question_answer
    Let the arithmetic mean and geometric mean of two numbers are 9 and 4 respectively. Then, these numbers are the roots of following equation

    A)  \[{{x}^{2}}+18x+16=0\]

    B)  \[{{x}^{2}}-18x+16=0\]

    C)  \[{{x}^{2}}+18x-16=0\]

    D)  \[{{x}^{2}}-18x-16=0\]

    Correct Answer: B

    Solution :

     Let\[\alpha \]and\[\beta \]are two numbers whose arithmetic mean is 9 and geometric mean is 4. \[\therefore \] \[\alpha +\beta =18,\alpha \beta =16\] Required equation is \[{{x}^{2}}-(\alpha -\beta )x+\alpha \beta =0\] \[\Rightarrow \] \[{{x}^{2}}-18x+16=0\]


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