Factoring in the Gaussian Integers

In summary, to factorise 70 into primes in Z[i], you can use the corollary that states if p is a prime in Z, then p is a prime in Z[i] if p = 3 mod 4. This means that 7 will remain prime in Z[i]. Additionally, if the norms of elements in Z[i] are congruent to 1 mod 4 and are prime in Z, then the elements in Z[i] are also prime. Therefore, 5 can be factored as (2+1)(2-i) in Z[i]. Putting it all together, 70 can be factorised into 7*(2+1)(2-i)*(1+i)(1-i).
  • #1
Firepanda
430
0
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
 
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  • #2
Yes, that's correct.
 

Related to Factoring in the Gaussian Integers

1. What are Gaussian integers?

Gaussian integers are complex numbers of the form a + bi, where a and b are both integers and i is the imaginary unit (√-1). They are named after the mathematician Carl Friedrich Gauss and have many applications in number theory and algebra.

2. How do you factor a Gaussian integer?

Factoring a Gaussian integer involves finding two other Gaussian integers that, when multiplied together, equal the original number. This can be done by using the same methods as factoring regular integers, such as finding common factors and using the distributive property.

3. What is the difference between factoring regular integers and factoring Gaussian integers?

The main difference is that Gaussian integers have two components (a and b) instead of just one (a). This means that when factoring, we have to consider both components and find two numbers that will multiply to equal the original Gaussian integer.

4. What are the applications of factoring in the Gaussian integers?

Factoring in the Gaussian integers is used in many areas of mathematics, including number theory, algebra, and cryptography. It is also used in solving Diophantine equations, which involve finding integer solutions to polynomial equations.

5. Can all Gaussian integers be factored?

Yes, all Gaussian integers can be factored into a product of other Gaussian integers. This is known as the unique factorization theorem for Gaussian integers, which states that every Gaussian integer can be expressed as a unique product of irreducible Gaussian integers.

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