Complex number inequality graph

In summary, Re(z) is the real part of z graphed only in the third quadrant, which is strange because it shouldn't be.
  • #1
Cpt Qwark
45
1

Homework Statement


How would Re(z)<0 be graphed?

Homework Equations


Re(z) is the real part of z

The Attempt at a Solution


It looks similar to y>x, but only shaded in the third quadrant, how can this be explained? not relevant anymore
 
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  • #2
Is there more to the problem?

Let z=x+iy, where x and y are real.
What is Re(z)?
 
  • #3
The question doesn't tell, but let's just assume z=x+iy.
 
  • #4
Cpt Qwark said:

Homework Statement


How would Re(z)<0 be graphed?

Homework Equations


Re(z) is the real part of z

The Attempt at a Solution


It looks similar to y>x, but only shaded in the third quadrant, how can this be explained?
I'm not sure I understand. It should be half the plane.
 
  • #5
I think i might be getting confused with the set notation,

if [tex]\alpha=\{z||x+iy|<n\}[/tex] and [tex]\beta=\{z|Re(z)>0\}[/tex], to graph [tex]\beta[/tex] would it just be the real part of [tex]\alpha?[/tex]
[tex]\{x,y,n\} \in \mathbb{R}[/tex]
 
  • #6
Cpt Qwark said:
I think i might be getting confused with the set notation,

if [tex]\alpha=\{z||x+iy|<n\}[/tex] and [tex]\beta=\{z|Re(z)>0\}[/tex], to graph [tex]\beta[/tex] would it just be the real part of [tex]\alpha?[/tex]
[tex]\{x,y\} \in \mathbb{R}[/tex]
Your definitions of alpha and beta are quite independent of each other, so why should there be any relationship between them?
Please post the question exactly as given.
 
  • #7
take [tex]\alpha=\{z||e^{iπ/4}(z+2)|<2\}[/tex] [tex](|e^{iπ}|=1)[/tex] and [tex]\beta=\{z|Re(z)>0\}[/tex],
how would beta be graphed?
 
  • #8
Cpt Qwark said:
take [tex]\alpha=\{z||e^{iπ/4}(z+2)|<2\}[/tex] [tex](|e^{iπ}|=1)[/tex] and [tex]\beta=\{z|Re(z)>0\}[/tex],
how would beta be graphed?
That cannot be the whole question since the information about alpha is irrelevant.
 
  • #9
haruspex said:
That cannot be the whole question since the information about alpha is irrelevant.
sorry, forgot graph[tex]\alpha∩\beta[/tex]
 
  • #10
Cpt Qwark said:
sorry, forgot graph[tex]\alpha∩\beta[/tex]
That makes a huge difference!
Ok, so what do you get for alpha and beta separately?
How would you combine the graphs to get the intersection?
 
  • #11
haruspex said:
That makes a huge difference!
Ok, so what do you get for alpha and beta separately?
How would you combine the graphs to get the intersection?

I can graph alpha which is just [tex]|z+2]<2[/tex] but for beta is it just the real part of alpha?
 
  • #12
Cpt Qwark said:
I can graph alpha which is just [tex]|z+2]<2[/tex] but for beta is it just the real part of alpha?
No, the graph of beta has no connection with alpha. Why do you think it should? Forget alpha for the moment and figure out what beta looks like.
Or, did you mean to ask whether the intersection of the two is just the real part of alpha?
 
  • #13
haruspex said:
No, the graph of beta has no connection with alpha. Why do you think it should? Forget alpha for the moment and figure out what beta looks like.
Or, did you mean to ask whether the intersection of the two is just the real part of alpha?

My original question was that I'm not sure how Re(z)>0 is graphed when there is no relation to alpha.
 
  • #14
Cpt Qwark said:
My original question was that I'm not sure how Re(z)>0 is graphed when there is no relation to alpha.
Ok. In the z=x+iy formulation, what does Re(z) look like in terms of x and y? What region of the complex plane does that correspond to?
 
  • #15
haruspex said:
Ok. In the z=x+iy formulation, what does Re(z) look like in terms of x and y? What region of the complex plane does that correspond to?
Oh, ok I get it now.
Thanks for your help!
 

Related to Complex number inequality graph

1. What is a complex number inequality graph?

A complex number inequality graph is a visual representation of inequalities involving complex numbers. The graph is typically plotted on a complex plane, with real numbers on the x-axis and imaginary numbers on the y-axis.

2. How do you graph a complex number inequality?

To graph a complex number inequality, first plot the boundary line or curve of the inequality on the complex plane. Then, choose a test point not on the boundary and plug it into the inequality. If the inequality is true for that point, shade the region containing the point. If it is false, shade the region not containing the point.

3. What is the purpose of graphing complex number inequalities?

The purpose of graphing complex number inequalities is to visually represent the solution set of the inequality. This can help in understanding the relationship between the complex numbers and identifying any patterns or trends.

4. How do you solve a system of complex number inequalities?

To solve a system of complex number inequalities, graph each inequality on the same complex plane and determine the overlapping region. The solution set will be the intersection of the solution sets for each individual inequality.

5. Can complex number inequalities have more than one solution?

Yes, complex number inequalities can have multiple solutions. The solution set may consist of individual points, regions, or even infinite solutions depending on the specific inequality.

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