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If for a complex number z,∣z∣−z=1+2iz,|z|-z=1+2iz,∣z∣−z=1+2i, then the value of z is​
Question

If for a complex number z,zz=1+2iz,|z|-z=1+2i, then the value of z is​

A.

232i2 - \frac{3}{2}i​​

B.

322i\frac{3}{2} - 2i​​

C.

32+2i\frac{3}{2} + 2i​​

D.

122i\frac{1}{2} - 2i​​

Correct option is B

Solution: zz=1+2iLet z=x+iy=>z=x2+y2=>x2+y2(x+iy)=1+2iEquating real and imaginary parts:x2+y2x=1(1)y=2=>y=2(2)Substitute (2) into (1):x2+4x=1=>x2+4=x+1Square both sides:x2+4=(x+1)2=x2+2x+1=>4=2x+1=>2x=3=>x=32So, z=322iFinal Answer: (B) 322i\textbf{Solution: }\\ |z| - z = 1 + 2i \\[8pt]\text{Let } z = x + iy \Rightarrow |z| = \sqrt{x^2 + y^2} \\[8pt]\Rightarrow \sqrt{x^2 + y^2} - (x + iy) = 1 + 2i \\[6pt]\textbf{Equating real and imaginary parts:} \\\sqrt{x^2 + y^2} - x = 1 \quad \text{(1)} \\-y = 2 \Rightarrow y = -2 \quad \text{(2)} \\[6pt]\text{Substitute (2) into (1):} \\\sqrt{x^2 + 4} - x = 1 \Rightarrow \sqrt{x^2 + 4} = x + 1 \\[6pt]\text{Square both sides:} \\x^2 + 4 = (x + 1)^2 = x^2 + 2x + 1 \\\Rightarrow 4 = 2x + 1 \Rightarrow 2x = 3 \Rightarrow x = \frac{3}{2} \\[8pt]\textbf{So, } z = \frac{3}{2} - 2i \\[10pt]\boxed{\text{Final Answer: (B) } \frac{3}{2} - 2i}​​

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