[Math] Find all complex numbers z for this equation

abstract-algebracomplex numberscomplex-analysis

I have been practicing some complex numbers and came across this problem.

Find all the complex numbers z that satisfie the equation $z + |z| = 8+4i$

I have said that $z = x + yi$ which means $|z| = \sqrt{x^2+y^2}$ which makes the equation

$x + yi + \sqrt{x^2 +y^2} = 8 + 4i$ but I dont know how to go from here to a solution?

Do I just have to rearrange a little or am I completely barking up the wrong tree?

Best Answer

You may first identify real part and imaginary part:

$$x + yi + \sqrt{x^2 +y^2} = 8 + 4i\implies x+ \sqrt{x^2 +y^2}=8, yi=4i $$

$$ y=4, x+ \sqrt{x^2 +16}=8 $$

$$x=3, y=4 \implies z=3+4i$$

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