Understanding the Roots of a Quadratic Equation

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SUMMARY

The discussion centers on understanding the roots of the polynomial equation x4 + 4, specifically the derivation of the zeros, which include ±(-1)1/4√2 and additional zeros involving the 3/4 power. Participants highlight the importance of roots of unity, noting that the fourth roots of unity (1, i, -1, -i) are crucial for solving the equation. The conversation emphasizes the need to factor the polynomial and explore the symmetry in its roots, which is essential for grasping the underlying concepts.

PREREQUISITES
  • Understanding of polynomial equations, specifically quartic equations
  • Familiarity with complex numbers and their properties
  • Knowledge of roots of unity and their significance in polynomial factorization
  • Basic skills in using computational tools like Wolfram Alpha for mathematical solutions
NEXT STEPS
  • Learn about polynomial factorization techniques, specifically for quartic equations
  • Study the concept of roots of unity in depth and their applications in solving equations
  • Explore the use of Wolfram Alpha for visualizing and solving complex polynomial equations
  • Practice deriving roots of polynomials using symmetry and complex number properties
USEFUL FOR

Students studying algebra, particularly those tackling polynomial equations, educators teaching complex numbers, and anyone interested in advanced mathematical problem-solving techniques.

nmsurobert
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Homework Statement


I'm looking for an explanation to something. I've attached a picture of the solution wolfram alpha is giving me.
I understand the first two zeros, +- (-1)^(1/4)*sqrt(2).
But i don't understand the other two zeros with the 3/4 power. Where does that power come from?
image.png


This isn't homework but it is course work. I thought I try some of the other problems out before diving into the actual homework and I'm already stuck lol.

Homework Equations

The Attempt at a Solution

 
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Just a few questions: Why don't you supply the link to Wolfram instead? This would definitely result in a better resolution.
Anyway, have you tried to factorize ##x^4 + 4## or to put it another way: what do you know about the roots of unity?
 
nmsurobert said:

Homework Statement


I'm looking for an explanation to something. I've attached a picture of the solution wolfram alpha is giving me.
I understand the first two zeros, +- (-1)^(1/4)*sqrt(2).
But i don't understand the other two zeros with the 3/4 power. Where does that power come from?
View attachment 105722

This isn't homework but it is course work. I thought I try some of the other problems out before diving into the actual homework and I'm already stuck lol.

Homework Equations

The Attempt at a Solution

The wolfram page mentions that these roots are multiples of the four fourth roots of unity (1). The fourth roots of 1 are i, -1, -1, and 1. They are equally spaced around the unit circle.
 
fresh_42 said:
Just a few questions: Why don't you supply the link to Wolfram instead? This would definitely result in a better resolution.
Anyway, have you tried to factorize ##x^4 + 4## or to put it another way: what do you know about the roots of unity?
Sorry. I'm on my phone and took a quick screen shot.
I haven't tried to factorize it yet. I'll give that a shot. I know there is some symmetry in factoring problems like that.
I don't know anything about roots of unity.
I figured there was some relation between the first two solutions being 1/4 power and the other two being 3/4 power. I'm assuming "roots of unity" plays a part there.
 
Thanks guys. The book has two pages on roots of unity that help with this problem.
 

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