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

  • question_answer
    If \[\alpha ,\beta ,\gamma \] and a, b, c are complex numbers such that \[\frac{\alpha }{a}+\frac{\beta }{b}+\frac{\gamma }{c}=1+i\] and \[\frac{a}{\alpha }+\frac{b}{\beta }+\frac{c}{\gamma }=0,\] then the value of \[\frac{{{\alpha }^{2}}}{{{a}^{2}}}+\frac{{{\beta }^{2}}}{{{b}^{2}}}+\frac{{{\gamma }^{2}}}{{{c}^{2}}}\] is equal to

    A) \[0\]                 

    B) \[-1\]   

    C) \[2i\]   

    D) \[-2i\]

    Correct Answer: C

    Solution :

    \[\frac{\alpha }{a}+\frac{\beta }{b}+\frac{\gamma }{c}=1+i\] squaring \[\frac{{{\alpha }^{2}}}{{{a}^{2}}}+\frac{{{\beta }^{2}}}{{{b}^{2}}}+\frac{{{\gamma }^{2}}}{{{c}^{2}}}+2\left( \frac{\alpha \beta }{ab}+\frac{\beta \gamma }{bc}+\frac{\gamma \alpha }{ac} \right)=2i\] or \[\frac{{{\alpha }^{2}}}{{{a}^{2}}}+\frac{{{\beta }^{2}}}{{{b}^{2}}}+\frac{{{\gamma }^{2}}}{{{c}^{2}}}+\frac{2\alpha \beta \gamma }{abc}\left( \frac{c}{\gamma }+\frac{a}{\alpha }+\frac{b}{\beta } \right)=2i\] \[\therefore \,\,\,\frac{{{\alpha }^{2}}}{{{a}^{2}}}+\frac{{{\beta }^{2}}}{{{b}^{2}}}+\frac{{{\gamma }^{2}}}{{{c}^{2}}}=2i\]


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