Solving Modulus Equation: Find z=a+bi

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Sorry about that.I fixed then end before, I just forgot to change the middle parts. Sorry about that.In summary, the problem is to find all complex numbers z=a+bi such that |z|=|z^2+1|. The attempt at a solution involved expanding the components and setting them equal to each other, but there was a mistake in the expansion which has been corrected. The next step would be to continue solving for the values of a and b that satisfy the equation.
  • #1
BloodyFrozen
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Homework Statement


Find all ##z=a+bi## such that:
[tex]|z|=|z^{2}+1|[/tex]


Homework Equations


The Attempt at a Solution


I expanded the components.
[tex]|z|=|z^{2}+1|[/tex]
[tex]z^{2}=a^2-b^2+2abi[/tex]
[tex]\sqrt{a^{2}+b^{2}}=\sqrt{(a^{2}-b^{2}+1)^{2}+(2ab)^{2}}[/tex]
[tex]a^2+b^2=(a^{2}-b^{2}+1)^{2}+(2ab)^{2}[/tex]
[tex]0=a^{4}+2a^{2}b^{2}+b^{4}+a^{2}-3b^{2}+1[/tex]

I don't see what to do now...
 
Last edited:
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  • #2
BloodyFrozen said:

Homework Statement


Find all ##z=a+bi## such that:
[tex]|z|=|z^{2}+1|[/tex]


Homework Equations


The Attempt at a Solution


I expanded the components.
[tex]|z|=|z^{2}+1|[/tex]
[tex]z^{2}=a^2+b^2+2abi[/tex]
That should be [itex]-b^2[/itex], not [itex]+b^2[/itex].
 
  • #3
jbunniii said:
That should be [itex]-b^2[/itex], not [itex]+b^2[/itex].

Right. Let me just go fix that.

Edit. Fixed
 
  • #4
BloodyFrozen said:
Right. Let me just go fix that.

Edit. Fixed

Well, you fixed it in the first line where it appeared, but you still need to fix it everywhere else.
 
  • #5
jbunniii said:
Well, you fixed it in the first line where it appeared, but you still need to fix it everywhere else.

I fixed then end before, I just forgot to change the middle parts.
 

1. What is a modulus equation?

A modulus equation is an equation that involves the modulus or absolute value of a complex number. It is typically written in the form |z| = a, where a is a real number.

2. How do you solve a modulus equation?

To solve a modulus equation, you first need to isolate the absolute value expression by rewriting the equation in two parts: one where the absolute value is positive and one where it is negative. Then, you can solve each part separately to find the solutions.

3. What is the significance of the "a+bi" in the equation?

The "a+bi" in the equation represents a complex number, where a is the real part and bi is the imaginary part. This notation is used to express complex numbers in the form a+bi, where i is the imaginary unit (√-1).

4. Can a modulus equation have more than one solution?

Yes, a modulus equation can have more than one solution. This is because the absolute value of a complex number can have two possible values: the positive value and the negative value. Therefore, the equation will have two solutions, unless the absolute value is equal to zero.

5. Are there any special cases when solving a modulus equation?

Yes, there are two special cases when solving a modulus equation. The first case is when the absolute value is equal to zero, in which case the equation has only one solution (z=0). The second case is when the absolute value is equal to a negative number, in which case the equation has no solutions.

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