JEE Main & Advanced Sample Paper JEE Main Sample Paper-20

  • question_answer
    The solution of the equation \[2z=|z|+2i\], where \[z\] is a complex number, is-

    A) \[z=\frac{\sqrt{3}}{3}-i\]                              

    B) \[z=\frac{\sqrt{3}}{3}+i\]

    C) \[z=\frac{\sqrt{3}}{3}+i\]                             

    D)  None of these

    Correct Answer: B

    Solution :

    \[2(x+iy)=\sqrt{{{x}^{2}}+{{y}^{2}}}+2i\]                 \[2x=\sqrt{{{x}^{2}}+{{y}^{2}}}\]and\[2y=2i.e.,\,\,y=1\]                 \[4{{x}^{2}}={{x}^{2}}+1\,\,i.e.,\,\,3{{x}^{2}}=1\,\,i.e.,\,\,x=\pm \frac{1}{\sqrt{3}}\]            \[x=\frac{1}{\sqrt{3}}(\because \,\,x\ge 0)\,\,\,\,\therefore z=\frac{1}{\sqrt{3}}+i=\frac{\sqrt{3}}{3}+i\]


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