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SSC Sample Paper Mock Test-1 SSC CGL Tear-II Paper-1

  • question_answer
    A and B solved a quadratic equation. In solving it, A made a mistake in the constant term and obtained the roots as 6 and 2, while B made a mistake in the coefficient of x only and obtained the roots\[-7\]and\[-1.\]Find the correct roots of the equation

    A) 2 or 1               

    B)  3 or 4

    C)  5 or 6              

    D)  7 or 1

    Correct Answer: D

    Solution :

    As obtained by A, we have \[\alpha +\beta =8\] and \[\alpha \beta =12\] \[\therefore \]The equation is \[{{x}^{2}}-8x+12=0\] As obtained by B, we have \[\alpha +\beta =-\,\,8\] and \[\alpha \beta =7\] \[\therefore \]The equation is\[{{x}^{2}}+8x+7=0\] Hence, the correct equation is \[{{x}^{2}}-8x+7=0\] Now, \[{{x}^{2}}-8x+7=0\Rightarrow {{x}^{2}}-7x-x+7=0\] \[\Rightarrow \]\[x(x-7)-1\,\,(x-7)=0\Rightarrow (x-7)(x-1)=0\] \[\Rightarrow \]   \[x=7\]or \[x=1\]           


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