Simple complex numbers question

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SUMMARY

The discussion centers on solving the equation z + (conjugate of z)^2 = 4, where z is defined as x + iy. The participants clarify the expansion of (conjugate of z)^2, leading to the expression x + x^2 - y^2. They derive that the imaginary part must equal zero, resulting in the conditions y = 0 or x = 1/2, alongside the equation x + x^2 - y^2 = 4. This analysis highlights the importance of correctly handling complex conjugates in algebraic expressions.

PREREQUISITES
  • Understanding of complex numbers, specifically the representation z = x + iy.
  • Familiarity with complex conjugates and their properties.
  • Knowledge of algebraic manipulation involving imaginary numbers.
  • Ability to solve polynomial equations in two variables.
NEXT STEPS
  • Study the properties of complex conjugates in detail.
  • Learn how to solve polynomial equations involving complex variables.
  • Explore the geometric interpretation of complex numbers on the complex plane.
  • Investigate the implications of imaginary parts equating to zero in complex equations.
USEFUL FOR

Students studying complex analysis, mathematics educators, and anyone looking to deepen their understanding of complex number operations and algebraic equations.

gtg177i
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Homework Statement


z+(conjugate of z)^2=4


Homework Equations


z = x+iy
(x+iy)+(x-iy)^2=4


The Attempt at a Solution


the solutions give (x+iy)+(x-iy)^2= x + x^2 - y^2. how do they reach that?
I get (x+iy)+(x-iy)^2 = x + iy + x^2 -2xiy + i^2*y^2.
I think the question is the ( conjugate of z )^2. e.g. z with the line on top of it and that squared.
Thanks!
 
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gtg177i said:

Homework Statement


z+(conjugate of z)^2=4


Homework Equations


z = x+iy
(x+iy)+(x-iy)^2=4


The Attempt at a Solution


the solutions give (x+iy)+(x-iy)^2= x + x^2 - y^2. how do they reach that?
They aren't showing all their steps.
x + iy + (x - iy)^2 = 4
==> x + iy + x^2 - y^2 -i2xy = 4
==> x + x^2 - y^2 + i(y - 2xy) = 4
Since the imaginary part of 4 is 0, it must be that y - 2xy = 0, or y(1 - 2x) = 0, which happens if y = 0 or if x = 1/2.

Then x + x^2 - y^2 = 4 and (y = 0 or x = 1/2)
gtg177i said:
I get (x+iy)+(x-iy)^2 = x + iy + x^2 -2xiy + i^2*y^2.
I think the question is the ( conjugate of z )^2. e.g. z with the line on top of it and that squared.
Thanks!
 

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