Abstract Algebra: a problem about ideal

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SUMMARY

The discussion focuses on the properties of the ideal J, defined as the set of all polynomials with a zero constant term in Z[x]. It is established that J is the principal ideal (x) in Z[x], meaning it is generated by the single element x. Furthermore, it is demonstrated that the quotient ring Z[x]/J contains an infinite number of distinct cosets, corresponding to each integer n in Z. This indicates that the structure of the quotient ring is rich and varied, reflecting the infinite nature of the integers.

PREREQUISITES
  • Understanding of polynomial rings, specifically Z[x]
  • Knowledge of ideal theory in ring theory
  • Familiarity with principal ideals and their properties
  • Basic concepts of quotient rings and cosets
NEXT STEPS
  • Study the definition and properties of principal ideals in ring theory
  • Learn about polynomial rings and their structure, focusing on Z[x]
  • Explore the concept of quotient rings and how to compute them
  • Investigate examples of distinct cosets in various algebraic structures
USEFUL FOR

Students of abstract algebra, particularly those studying ring theory, as well as educators looking to enhance their understanding of ideals and polynomial rings.

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Homework Statement


Let J be the set of all polynomials with zero constant term in Z[x]. (Z=integers)
a.) Show that J is the principal ideal (x) in Z[x].
b.) Show that Z[x]/J consists of an infinite number of distinct cosets, one for each n\inZ.


Homework Equations





The Attempt at a Solution


I have trouble understanding what a principal ideal is. Any help on how I should start would be great. Thanks!
 
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Well, what's the set generated by {x} in Z(x)? Isn't it just x*Z(x)? What's that?
 
An ideal is a subset of a ring that's closed under addition of its own elements and under multiplication by anything in the ring. A principal ideal is one that's generated by one element.

So, take an element in Z[x] and multiply it by x. Whatever you get, by definition, is in the ideal (x). What do those things look like?

Now, two things are in the same coset of Z[x]/J if their difference is in J. So, if I can subtract off any polynomial I want with zero constant term, what stays unchanged?
 

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