JEE Main & Advanced Mathematics Complex Numbers and Quadratic Equations Question Bank Self Evaluation Test - Complex Numbers and Quadratic Equations

  • question_answer
    If \[{{z}_{1}},{{z}_{2}}\] are the roots of the quadratic equation \[a{{z}^{2}}+bz+c=0\] such that \[\operatorname{Im}({{z}_{1}},{{z}_{2}})\ne 0\] then

    A) a, b, c are all real

    B) at least one of a, b, c is real

    C) at least one of a, b, c is imaginary

    D) all of a, b, c are imaginary

    Correct Answer: C

    Solution :

    Since \[\operatorname{a}{{z}^{2}}+bz+c=0\]   .... (1) and \[{{z}_{1}},\,\,{{z}_{2}}\] (roots of (1)) are such that Im \[({{z}_{1}}{{z}_{2}})\ne 0\]. Now, \[{{\operatorname{z}}_{1}}\,\,and\,\,{{z}_{2}}\] are not conjugates of each other Complex roots of (1) are not conjugate of each other Coefficient a, b, c cannot all be real at least one of a, b, c, is imaginary.


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