CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2003

  • question_answer
    The quadratic equation whose roots are twice the roots of\[2{{x}^{2}}-5x+2=0\]is:

    A)  \[8{{x}^{2}}-10x+2=0\]

    B)  \[{{x}^{2}}-5x+4=0\]

    C)  \[2{{x}^{2}}-5x+2=0\]

    D)  \[{{x}^{2}}-10x+6=0\]

    E)  none of the above

    Correct Answer: B

    Solution :

    Let the roots of the equation\[2{{x}^{2}}-5x+2=0\] are\[\alpha \]and\[\beta \]. Then \[\alpha +\beta =\frac{5}{2}\]and\[\alpha \beta =1\] Now, the roots of required equation be\[2\alpha \] and\[2\beta \]. \[\therefore \]Sum of roots\[=2(\alpha +\beta )=5\] and product of roots\[=2\alpha .2\beta \]                                 \[=4\alpha \beta \] \[=4\] \[\therefore \]Required equation is \[{{x}^{2}}-5x+4=0\]


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