Factoring polynomials over real and complex numbers

In summary, the conversation is about factorizing z^8 - 15z^4 - 16 over the complex and real numbers. The attempt at a solution involves substituting z = (x + iy) and expanding and separating real from complex terms. However, since the powers are to the 8, this method seems unlikely. The difference between factoring over the complex and real numbers is also mentioned.
  • #1
NewtonianAlch
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Homework Statement


Factorise z[itex]^{8}[/itex] -15z[itex]^{4}[/itex] - 16 over the Complex numbers and Real numbers


The Attempt at a Solution



I factorised over the complex numbers, I'm not sure what they mean by over the real numbers.

Do I substitute z = (x + iy) and then do it by expanding and separating real from complex? I would have tried it at first, except these are powers to the 8, which seems like an unlikely method.
 
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  • #2
Hi NewtonianAlch! :smile:
NewtonianAlch said:
I factorised over the complex numbers, I'm not sure what they mean by over the real numbers.

over the complex numbers means that the factors have (possibly) complex coefficients (and will all be linear)

over the real numbers means that the factors have real coefficients (and will be either linear or quadratic) :wink:
 

Related to Factoring polynomials over real and complex numbers

1. What is factoring over real numbers?

Factoring over real numbers is the process of finding the factors of a polynomial expression with real coefficients. This means breaking down the expression into simpler terms that can be multiplied to give the original expression.

2. Why is factoring over real numbers important?

Factoring over real numbers is important because it allows us to simplify polynomial expressions and find their roots. This helps in solving equations, graphing functions, and understanding the behavior of polynomial functions.

3. How do you factor a polynomial over real numbers?

To factor a polynomial over real numbers, we use the techniques of grouping, finding common factors, and using the quadratic formula for quadratic expressions. The goal is to write the polynomial as a product of simpler terms.

4. Can all polynomials be factored over real numbers?

Yes, all polynomials with real coefficients can be factored over real numbers. This is known as the Fundamental Theorem of Algebra. However, some polynomials may have complex factors, which are not real numbers.

5. What is the difference between factoring over real numbers and factoring over complex numbers?

The main difference between factoring over real numbers and factoring over complex numbers is that complex numbers include imaginary numbers, while real numbers do not. This means that factoring over complex numbers can result in more factors than factoring over real numbers.

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