Prove Nth Roots of Unity: \omega, \overline{\omega}, \omega^{r}

In summary, to prove that \overline{\omega} and \omega^{r} are nth roots of unity if \omega is an nth root of unity, simply use the property that an nth root of unity satisfies w^n=1. Conjugate \omega and then raise both sides to the power r to show that \overline{\omega} and \omega^{r} also satisfy this property.
  • #1
gotmilk04
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Homework Statement


Show that, if [tex]\omega[/tex] is an nth root of unity, then so are [tex]\overline{\omega}[/tex] and [tex]\omega^{r}[/tex] for every integer r.


Homework Equations


[tex]\omega[/tex]=r[tex]^{1/n}[/tex]e[tex]^{i((\theta+2\pi)/n)}[/tex]


The Attempt at a Solution


I got the first part and for [tex]\omega^{r}[/tex] I have it equals
e[tex]^{i(r2\pi/n)}[/tex]
but what more do I need to do/show to prove it's an nth root of unity?
 
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  • #2
There's no need to use an explicit form for w. An nth root of unity satisfies w^n=1. Just use that. Take the conjugate and then raise both sides to the power r.
 

1. What are the Nth roots of unity?

The Nth roots of unity are complex numbers that, when raised to the power of N, equal 1. In other words, they are solutions to the equation x^N = 1.

2. How do you prove the Nth roots of unity?

The most common method for proving the Nth roots of unity is by using De Moivre's formula, which states that for any complex number z = r(cosθ + isinθ), raising it to the power of N will result in z^N = r^N(cos(Nθ) + isin(Nθ)). By setting z^N = 1 and solving for θ, we can find the N distinct solutions for the Nth roots of unity.

3. What is the significance of the Nth roots of unity?

The Nth roots of unity have important applications in fields such as number theory, algebra, and geometry. They also have connections to various mathematical concepts such as symmetry, group theory, and the roots of polynomial equations.

4. What are the three main Nth roots of unity?

The three main Nth roots of unity are represented by the symbols ω, ω^r, and ω^r2, where ω = e^(2πi/N) and r is a positive integer less than N. These roots are sometimes referred to as the principal root, the conjugate root, and the conjugate of the conjugate root, respectively.

5. How are the Nth roots of unity related to each other?

The Nth roots of unity are related to each other through conjugation and exponentiation. For example, ω and ω^r are conjugates of each other, and ω^r and ω^r2 are conjugates of each other. Additionally, ω^r can be obtained by raising ω to the power of r.

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