Math Problem Statement

z^3 $$$$ -1=0

Solution

The equation to solve is:

z31=0z^3 - 1 = 0

Step 1: Rewrite the equation

Rewriting the equation, we have:

z3=1z^3 = 1

This represents the complex cube roots of unity.

Step 2: Represent 1 in polar form

The number 11 can be represented in polar form as:

1=ei2πk,kZ1 = e^{i 2\pi k}, \quad k \in \mathbb{Z}

Here, kk represents the possible angles as multiples of 2π2\pi. For cube roots, we divide the angle 2πk2\pi k by 33.

Step 3: General solution

The cube roots of unity are given by:

z=ei2πk3,k=0,1,2z = e^{i \frac{2\pi k}{3}}, \quad k = 0, 1, 2

Step 4: Write each solution explicitly

  1. For k=0k = 0: z0=ei2π03=ei0=1z_0 = e^{i \frac{2\pi \cdot 0}{3}} = e^{i 0} = 1

  2. For k=1k = 1: z1=ei2π13=ei2π3=12+i32z_1 = e^{i \frac{2\pi \cdot 1}{3}} = e^{i \frac{2\pi}{3}} = -\frac{1}{2} + i \frac{\sqrt{3}}{2}

  3. For k=2k = 2: z2=ei2π23=ei4π3=12i32z_2 = e^{i \frac{2\pi \cdot 2}{3}} = e^{i \frac{4\pi}{3}} = -\frac{1}{2} - i \frac{\sqrt{3}}{2}

Final Solutions

The three cube roots of unity are:

z0=1,z1=12+i32,z2=12i32.z_0 = 1, \quad z_1 = -\frac{1}{2} + i \frac{\sqrt{3}}{2}, \quad z_2 = -\frac{1}{2} - i \frac{\sqrt{3}}{2}.

Visualization Tip

These roots are evenly spaced on the unit circle in the complex plane, at angles 00, 2π3\frac{2\pi}{3}, and 4π3\frac{4\pi}{3}.


Would you like further clarification or a detailed geometric representation of the roots?

Here are some related questions for deeper understanding:

  1. What is the significance of cube roots of unity in mathematics?
  2. How do the cube roots of unity relate to polynomial factorization?
  3. Can we derive the same roots using factorization of z31z^3 - 1?
  4. What are the properties of the cube roots of unity?
  5. How can we visualize these roots in the Argand plane?

Tip: The sum of all cube roots of unity is always zero, which is a useful property!

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Math Problem Analysis

Mathematical Concepts

Algebra
Complex Numbers
Roots of Unity

Formulas

Polar form: z = e^{iθ}
General formula for nth roots: z_k = e^{i(2πk/n)}
Factorization: z^n - 1 = (z - 1)(z^{n-1} + z^{n-2} + ... + z + 1)

Theorems

Fundamental Theorem of Algebra
Properties of Roots of Unity

Suitable Grade Level

Grades 10-12