Factorizing a polynomial over a ring

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Homework Help Overview

The discussion revolves around factorizing the polynomial x^2 + x + 8 in the ring \mathbb{Z}_{10}[x]. Participants are exploring different methods to achieve this factorization and are particularly interested in systematic approaches.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss identifying roots of the polynomial and their corresponding factorizations. There is mention of finding pairs of numbers that satisfy specific modular conditions related to the sum and product of the roots.

Discussion Status

The conversation includes attempts to clarify the factorization process and whether it can be approached systematically. Some participants express that the method may involve trial and error, while others suggest that it can be organized in a more systematic manner.

Contextual Notes

There is an emphasis on using modular arithmetic and the constraints of working within \mathbb{Z}_{10}. Participants are considering the implications of these constraints on their factorization attempts.

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Homework Statement


Factorize x^2 + x + 8 in \mathbb{Z}_{10}[x] in two different ways

Homework Equations


The Attempt at a Solution


I can see that x = 8 = -2 and x = 1 = -9 are roots of the polynomial, so one factorization is (x + 2)(x + 9).

Is there a systematic way to find all the factorizations?
 
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I just looked at the various ways to get a product of 8 mod 10, the look at the sum of those products. I immediately see that 2*9= 18= 8 mod 10 and 2+ 9= 11= 1 mod 10 and that 4*7= 28= 8 mod 10 and that 4+ 7= 11= 1 mod 10.
 
Adorno said:

Homework Statement


Factorize x^2 + x + 8 in \mathbb{Z}_{10}[x] in two different ways


Homework Equations





The Attempt at a Solution


I can see that x = 8 = -2 and x = 1 = -9 are roots of the polynomial, so one factorization is (x + 2)(x + 9).

Is there a systematic way to find all the factorizations?
It looks like the "Master Product rule"form introductory algebra --- only here you use modular arithmetic.

You are looking for a pair of numbers whose sum is 1 (mod 10) and whose product is 8 (mod 10).
 
So, it's essentially just trial and error?
 
Adorno said:
So, it's essentially just trial and error?
Yes, but it's somewhat systematic trial & error.
 

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