Factoring in the Gaussian Integers

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SUMMARY

The discussion focuses on factoring the integer 70 into its prime components within the Gaussian integers, Z[i]. The prime factors identified are 2, 5, and 7, with 2 being factored as (1+i)(1-i). The participant confirms that 7 remains prime in Z[i] due to the corollary stating that a prime p in Z is also prime in Z[i] if p ≡ 3 mod 4. Additionally, the number 5 is factored as (2+1)(2-i), leading to the complete factorization of 70 as 70 = 7*(2+1)(2-i)*(1+i)(1-i).

PREREQUISITES
  • Understanding of Gaussian integers (Z[i])
  • Knowledge of prime factorization in integers
  • Familiarity with modular arithmetic, specifically mod 4
  • Basic concepts of norms in number theory
NEXT STEPS
  • Study the properties of Gaussian integers and their prime elements
  • Learn about the norms of elements in Z[i] and their implications for primality
  • Explore advanced factorization techniques in algebraic number theory
  • Investigate the relationship between modular arithmetic and primality in different integer rings
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Mathematicians, number theorists, and students interested in algebraic structures, particularly those studying prime factorization in Gaussian integers.

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I need to factorise 70 into primes, how do I go about this?

So far I have 2,5,7 as primes in Z.

So I suppose I need to factorise these in Z?

2 = (1+i)(1-i)

How do I go around doing the other two, is it possible that they're primes in Z?

Edit:

I have a corollary where if p is a prime in Z, then p is a prime in Z if p = 3 mod 4

So 7 stays prime in Z.

Also I have that if the norms of elements in Z are congruent to 1 mod 4 and prime in Z, then the elements in Z are prime, so

5 = (2+1)(2-i) = 1 mod 4

so 70 = 7*(2+1)(2-i)*(1+i)(1-i)

Correct?

Thanks
 
Last edited:
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Yes, that's correct.
 

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