Complex numbers and reflection

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Homework Help Overview

The discussion revolves around the reflection of a line represented in the complex plane, specifically the equation ##\bar{a}z + a\bar{z} = 0##, and how to determine its reflection in the real axis. Participants are exploring concepts related to complex geometry and the properties of complex conjugates.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the representation of lines in the complex plane and the implications of taking the conjugate of complex numbers. There is uncertainty about how to reflect the line and whether to conjugate the entire equation or just specific terms.

Discussion Status

Some participants have offered insights regarding the reflection process and the nature of complex conjugates, while others express confusion about the relationship between the original line and its reflection. The conversation is ongoing, with various interpretations being explored.

Contextual Notes

There is mention of the participants' varying levels of familiarity with complex geometry, which may influence their understanding of the problem. Additionally, the discussion includes questions about the general rules for reflecting points and lines in the complex plane.

erisedk
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Homework Statement


Reflection of the line ##\bar{a}z + a\bar{z} = 0## in the real axis is

Homework Equations

The Attempt at a Solution


I know that a line in the complex plane is represented as ##\bar{a}z + a\bar{z} + b= 0## and that its slope ##μ = \dfrac{-a}{\bar{a}}##. I'm not sure how to do this problem. I'm also not very good with complex geometry so please help.
 
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erisedk said:

Homework Statement


Reflection of the line ##\bar{a}z + a\bar{z} = 0## in the real axis is

Homework Equations

The Attempt at a Solution


I know that a line in the complex plane is represented as ##\bar{a}z + a\bar{z} + b= 0## and that its slope ##μ = \dfrac{-a}{\bar{a}}##. I'm not sure how to do this problem. I'm also not very good with complex geometry so please help.
What is the reflection of z in the real axis?
 
Its conjugate.
 
erisedk said:
Its conjugate.
Right. So if you have two points ##z## and ##\bar w##, how would you write their reflections notationally? What is the general rule you see here?
 
As ##\bar{z}## and ##w##? That I need to take the conjugate of the equation of the line? But that gives me back the original line. However, the funny thing is if I take the conjugate of only ##z##, I get the desired answer, i.e. ##\bar{a}\bar{z} + az = 0##. I can't really explain that though.
 
erisedk said:
However, the funny thing is if I take the conjugate of only ##z##, I get the desired answer, i.e. ##\bar{a}\bar{z} + az = 0##. I can't really explain that though.
You need to conjugate those complex numbers z which are on that line instead of conjugating the equation.
You have a line in the x,y plane. What is the equation of that line?
What line do you get when you reflect the original line on the x axis?
How can you write the complex numbers z1 with their real and imaginary parts which are on the original line ? What are those complex numbers z2 which are on the reflected line?
 
erisedk said:
As ##\bar{z}## and ##w##? That I need to take the conjugate of the equation of the line? But that gives me back the original line. However, the funny thing is if I take the conjugate of only ##z##, I get the desired answer, i.e. ##\bar{a}\bar{z} + az = 0##. I can't really explain that though.
If you have an equation for z that specifies a point, z=a say, then how do you write the equation for the reflection of that point? You would write ##\bar z=a## or ##z=\bar a##, not ##\bar z=\bar a##.
 
Ok, got it thank you!
 

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