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

  • question_answer
    If z is a complex number such that \[z+|z|=8+12i,\] then the value of \[|{{z}^{2}}|\] is equal to

    A) 228      

    B) 144 

    C) 121      

    D) 169

    Correct Answer: D

    Solution :

    \[z+|z|=8+12i\] \[\Rightarrow \,\,\,\,x+iy+\sqrt{{{x}^{2}}+{{y}^{2}}}=8+12i\] \[\Rightarrow \,\,\,\,x+\sqrt{{{x}^{2}}+{{y}^{2}}}=8\]     ...(i)     &   \[y=12\]   ...(ii) \[(x=-5)\] So, \[z=-5+12i\] \[\Rightarrow \,\,\,\,|z|=\sqrt{25+144}=13\]    \[\Rightarrow \,\,\,|{{z}^{2}}|=|z{{|}^{2}}=169\]


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