Proving a Factor of Complex Cube Root of 1 in x^3 + y^3 + z^3 - 3xyz Equation

In summary, the equation x + wy + w^2z is a factor of the polynomial x^3 + y^3 + z^3 - 3xyz if the remainder of dividing x^3 + y^3 + z^3 - 3xyz by x + wy + w^2z is equal to zero. Additionally, if z^3 = 1, then z^3 - 1 can be factored into (z-1)(z^2+z+1)=0, which means that w^2 + w + 1 = 0. By putting x = -w, the polynomial becomes zero, thus proving that x + wy + w^2z is a factor of x^3
  • #1
Ferrus
13
0

Homework Statement



If w is a complex cube root of 1, prove that x + wy + w^2z is a factor of x^3+ y^3 + z^3 - 3xyz, and hence factorise the equation completely.

Homework Equations



Complex cube root of 1 = -1/2 +/- 3^1/2/2 i

The Attempt at a Solution



Erm, I feel way over my head. I have tried plugging in the equation to the first one but this doesn't seem to generate anything intelligible for me.
 
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  • #2
Hi Ferrus, welcome to PF:smile:

Hint 1: If [itex]x + wy + w^2z[/itex] is a factor of [itex]x^3+ y^3 + z^3 - 3xyz[/itex], what can you say about the remainder of [tex]\frac{x^3+ y^3 + z^3 - 3xyz}{x + wy + w^2z}[/tex]

Hint 2: If [itex]z^3=1[/itex], then [itex]z^3-1=(z-1)(z^2+z+1)=0[/itex]... so what can you say about [itex]w^2+w+1[/itex]?
 
  • #3
Welcome to PF!

Ferrus said:
If w is a complex cube root of 1, prove that x + wy + w^2z is a factor of x^3+ y^3 + z^3 - 3xyz …

Hi Ferrus ! Welcome to PF! :smile:

Hint: if (x+a) is a factor of a polynomial, then put x = -a and the polynomial will be zero …

so put x = … ? :wink:
 

Related to Proving a Factor of Complex Cube Root of 1 in x^3 + y^3 + z^3 - 3xyz Equation

What is the complex cube root of 1?

The complex cube root of 1 is a mathematical concept that refers to the three complex numbers that, when multiplied together, result in 1. These numbers are known as the cube roots of 1.

What are the three solutions to the complex cube root of 1?

The three solutions to the complex cube root of 1 are 1, (-1 + √3i)/2, and (-1 - √3i)/2. These three numbers, when multiplied together, equal 1.

How do you calculate the complex cube root of 1?

The complex cube root of 1 can be calculated by using the formula:
1^(1/3) = e^(2πki/3), where k = 0, 1, 2. This formula will give the three solutions mentioned above.

What is the relationship between the complex cube root of 1 and the unit circle?

The three solutions to the complex cube root of 1 can be represented on the unit circle, with each solution corresponding to a point on the circle. This is because the solutions are complex numbers in the form of a + bi, where a and b represent the coordinates on the unit circle.

Why is the complex cube root of 1 important in mathematics?

The complex cube root of 1 is important in mathematics because it is a fundamental concept in understanding complex numbers and their properties. It is also used in various mathematical equations and applications, such as in engineering and physics.

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