Simple complex numbers question

In summary, the given equation can be solved by expanding the conjugate of z squared and setting the real and imaginary parts equal to 4. The solutions are x + x^2 - y^2 = 4 and (y = 0 or x = 1/2).
  • #1
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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  • #2
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!
 

1. What are complex numbers?

Complex numbers are numbers that consist of a real part and an imaginary part. They are written in the form a + bi, where a is the real part and bi is the imaginary part represented by the square root of -1, also known as i.

2. How do you add and subtract complex numbers?

To add or subtract complex numbers, you simply add or subtract the real parts and the imaginary parts separately. For example, (3 + 2i) + (5 + 4i) = (3 + 5) + (2i + 4i) = 8 + 6i.

3. What is the conjugate of a complex number?

The conjugate of a complex number is when the sign of the imaginary part is changed. For example, the conjugate of 3 + 4i is 3 - 4i. This is important when dividing complex numbers.

4. How do you multiply and divide complex numbers?

To multiply complex numbers, you use the FOIL method (First, Outer, Inner, Last). For example, (3 + 2i)(5 + 4i) = 15 + 12i + 10i + 8i^2 = 7 + 22i. To divide complex numbers, you multiply the numerator and denominator by the conjugate of the denominator and simplify.

5. What is the absolute value of a complex number?

The absolute value of a complex number is the distance of the number from the origin on the complex plane. It is calculated by taking the square root of the sum of the squares of the real and imaginary parts. For example, the absolute value of 3 + 4i is √(3^2 + 4^2) = √25 = 5.

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