Ideal and Factor Ring Problem: Proving A=R When 1 is an Element of A

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SUMMARY

In the discussion, participants analyze the proof that if A is an ideal of a ring R and 1 is an element of A, then A must equal R. The key argument presented is that since A is an ideal, for any element r in R, the product ar (where a is in A) must also be in A. This leads to the conclusion that the multiplicative identity 1 being in A implies that all elements of R can be generated from A, thus proving A = R. The discussion emphasizes the properties of ideals in ring theory.

PREREQUISITES
  • Understanding of ring theory and the definition of an ideal.
  • Familiarity with the properties of ring elements and multiplication.
  • Knowledge of the concept of the multiplicative identity in rings.
  • Basic proof techniques in abstract algebra.
NEXT STEPS
  • Study the properties of ideals in ring theory.
  • Learn about the structure of rings and their elements.
  • Explore examples of ideals in specific rings, such as integers and polynomial rings.
  • Review proof techniques in abstract algebra, focusing on direct proofs and contradiction.
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Students of abstract algebra, mathematicians focusing on ring theory, and anyone interested in understanding the properties of ideals and their implications in algebraic structures.

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Homework Statement



If A is an ideal of a ring R and 1 belongs to A, prove that A=R.

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The Attempt at a Solution



I said that r should an element of R. and since A is ideal to ring R and 1 is an element of A , then ar should be an element of A . 1 must be an element of a which is an element of ar which is an element of A. Therefore 1*ra=ar*1=> 1 is an element of R. Therefore,R=A
 
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1 must be an element of a doesn't mean anything... what the heck is a supposed to be anyway? I'm assuming it's an element of A maybe... at any rate, nothing can be an element of ar as ar is simply a member of the ring, and you have no reason to believe it's a set.

You realize an ideal is defined such that if a is in A, then for all x in R, x*a is in A?
 

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