JEE Main & Advanced AIEEE Solved Paper-2008

  • question_answer
    The quadratic equations \[{{x}^{2}}-6x+a=0\] and \[{{x}^{2}}-cx+6=0\] have one root in common. The other roots of the first and second equations are integers in the ratio 4 : 3. Then the common root is       AIEEE  Solved  Paper-2008

    A) 3                             

    B)        2                             

    C)        1                             

    D)        4

    Correct Answer: B

    Solution :

                    Let the roots of \[{{x}^{2}}-6x+a=0\] and the roots of \[{{x}^{2}}-cx+6=0\] be \[\alpha ,\,\,3\beta \] \[\therefore \,\,\alpha +4\beta =6\]                       ? (i) \[4\,\,\alpha \beta =a\]                                ? (ii) \[\alpha +3\beta =c\]                     ? (iii) and \[3\alpha \beta =6\]                              ? (iv) (ii) and (iv) \[\Rightarrow \,\,a=8\] \[\therefore \] 1st equation reduces to \[{{x}^{2}}-6x+8=0\] Clearly \[\alpha =2\] and \[\beta =1\] \[\therefore \] Common root is 2.


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