Solving Complex Number Question z^3+i=0 using z^n=|z|^(n) x e^((i)(n)(theta))

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SUMMARY

The discussion centers on solving the complex number equation z3 + i = 0, which simplifies to z3 = -i. Participants emphasize the importance of expressing -i in polar form as r·e(iθ) and dividing the angle θ by 3 to find the roots. The correct approach involves identifying |z| as 1 and θ as -π/2, leading to three distinct solutions for z. The conversation highlights the necessity of a step-by-step logical approach to avoid mistakes in complex number calculations.

PREREQUISITES
  • Understanding of complex numbers and their polar representation
  • Familiarity with De Moivre's Theorem
  • Knowledge of Euler's formula e(iθ) = cos(θ) + i sin(θ)
  • Basic algebraic manipulation of complex equations
NEXT STEPS
  • Study the polar form of complex numbers in detail
  • Learn about De Moivre's Theorem and its applications
  • Explore the concept of roots of complex numbers
  • Investigate the geometric interpretation of complex number equations
USEFUL FOR

Mathematicians, engineering students, and anyone interested in complex analysis or solving polynomial equations involving complex numbers.

Ry122
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Find z
Question:
z^3+i=0
My attempt:
z^3=-i
use z^n=|z|^(n) x e^((i)(n)(theta))
n = 3
|z|=1
theta = -pie/2
Is this correct?
 
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if z=i

z^2=-1 z^3=-1*i >>-i
 
… one step at a time …

Ry122 said:
z^3+i=0
My attempt:
z^3=-i
use z^n=|z|^(n) x e^((i)(n)(theta))

Hi Ry122! :smile:

You must be much more logical, or you'll make mistakes. :frown:

Do it one step at a time.

You know z^3=-i.

So - first step - write -i in the form r.e^(i theta).

What is it?

Then divide theta by 3. :smile:

Oh … and how many different solutions are there? :rolleyes:
 

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