JAMIA MILLIA ISLAMIA Jamia Millia Islamia Solved Paper-2006

  • question_answer
        If\[\alpha ,\beta \]be the two roots of the equation \[{{x}^{2}}+x+1=0,\]then the equation whose roots are \[\frac{\alpha }{\beta }\]and \[\frac{\beta }{\alpha }\]is

    A)  \[{{x}^{2}}+x+1=0\]      

    B)  \[{{x}^{2}}-x+1=0\]

    C)  \[{{x}^{2}}-x-1=0\]        

    D)  \[{{x}^{2}}+x-1=0\]

    Correct Answer: A

    Solution :

                    Given a and p are roots of \[{{x}^{2}}+x+1=0\] \[\Rightarrow \]               \[\alpha +\beta =-1\] and           \[\alpha \beta =1\] Now, \[\frac{\alpha }{\beta }+\frac{\beta }{\alpha }=\frac{{{\alpha }^{2}}+{{\beta }^{2}}}{\alpha \beta }=\frac{(\alpha +{{\beta }^{2}})-2\alpha \beta }{\alpha \beta }\]                                 \[=\frac{1-2}{1}=-1\] \[\frac{\alpha }{\beta }.\frac{\beta }{\alpha }=1\] \[\therefore \]Equation having roots \[\frac{\alpha }{\beta }\]and\[\frac{\beta }{\alpha }\]is \[{{x}^{2}}+x+1=0\]


You need to login to perform this action.
You will be redirected in 3 sec spinner