JAMIA MILLIA ISLAMIA Jamia Millia Islamia Solved Paper-2013

  • question_answer
        The sum of the non-real roots of\[({{x}^{2}}+x-2)({{x}^{2}}+x-3)=12\]is

    A)  1                                            

    B)  \[-1\]

    C)  \[-6\]                                   

    D)  6

    Correct Answer: B

    Solution :

                    Put \[{{x}^{2}}+x=y\] So that, the equation becomes \[(y-2)(y-3)=12\] \[\Rightarrow \]               \[{{y}^{2}}-5y-6=0\] \[\Rightarrow \]               \[(y-6)(y+1)=0\] \[\therefore \]  \[y=6,-1\] When\[y=6,\]then we get \[{{x}^{2}}+x-6=0\] \[\Rightarrow \]               \[(x+3)(x-2)=0\] \[\therefore \]  \[x=-3,2\] When\[y=-1,\]then we get \[{{x}^{2}}+x+1=0\] \[\Rightarrow \]               \[x=\omega ,{{\omega }^{2}}\] and their sum is\[\omega +{{\omega }^{2}},\]i.e., \[(-1)\] \[(\because 1+\omega +{{\omega }^{2}}=0)\]


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