JEE Main & Advanced Mathematics Complex Numbers and Quadratic Equations Question Bank Relation between roots and coefficients

  • question_answer
    The equation of the smallest degree with real coefficients having \[1+i\] as one of the root is [Kerala (Engg.) 2002]

    A) \[{{x}^{2}}+x+1=0\]

    B) \[{{x}^{2}}-2x+2=0\]

    C) \[{{x}^{2}}+2x+2=0\]

    D) \[{{x}^{2}}+2x-2=0\]

    Correct Answer: B

    Solution :

    Let \[x=1+i\Leftrightarrow x-1=i\] \[\Leftrightarrow {{(x-1)}^{2}}={{i}^{2}}\Leftrightarrow {{x}^{2}}-2x+1=-1\] \[\Leftrightarrow {{x}^{2}}-2x+2=0\].


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