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# What are the maximal ideals of Z X?

## What are the maximal ideals of Z X?

Maximal ideals of Z[x]. The maximal ideals of Z[x] are of the form (p, f(x)) where p is a prime number and f(x) is a polynomial in Z[x] which is irreducible modulo p. To prove this let M be a maximal ideal of Z[x].

## Which of the given ideas is a maximal ideal of Z?

If F is a field, then the only maximal ideal is {0}. In the ring Z of integers, the maximal ideals are the principal ideals generated by a prime number. More generally, all nonzero prime ideals are maximal in a principal ideal domain.

Is 2 X a maximal ideal?

Since Z2 is a field, (2,x) is a maximal ideal. An ideal P is called a prime ideal if P R and whenever the product ab ∈ P for a,b ∈ R, then at least one of a or b is in P . Example 42. In any integral domain, the 0 ideal (0) is a prime ideal.

What are the ideals of Z?

1 Ideals of Integers. Recall that Z = {0, −1, 1, −2, 2, −3, 3,… } is the set of integers. If n ∈ Z is any. integer, we write nZ for the set.

• 2 Least common multiple, greatest common divisor. Let us compute some instances of Theorem 1.6. We compute k and d for various different values of n and m. 4Z ∩ 6Z = 12Z.
• 3 Exercises.
• ### What are the prime ideals of Z X?

(1) The prime ideals of Z are (0),(2),(3),(5),…; these are all maximal except (0). (2) If A = C[x], the polynomial ring in one variable over C then the prime ideals are (0) and (x − λ) for each λ ∈ C; again these are all maximal except (0).

### Why is the ideal 6Z not a maximal ideal of Z?

Example: The ideal 6Z is not maximal in Z because 6Z ⊊ 2Z⊊Z. To see this suppose 7Z ⊊ B ⊆ R, then there is some b ∈ B with b ∈ 7Z and so gcd (7,b) = 1 and so there exist x, y ∈ Z with 7x+by = 1.

Are all prime ideals maximal?

(1) An ideal P in A is prime if and only if A/P is an integral domain. (2) An ideal m in A is maximal if and only if A/ m is a field. Of course it follows from this that every maximal ideal is prime but not every prime ideal is maximal.

Is Z an ideal of Q?

So (0) is indeed maximal in Q. On the other hand, it is not maximal in Z. For example, I=2Z is a proper ideal which properly contains (0). Q∗ is not a field, not even a ring, since it has not neutral element for addition.

#### How do you know if an ideal is maximal?

An ideal m in a ring A is called maximal if m = A and the only ideal strictly containing m is A. Exercise. (1) An ideal P in A is prime if and only if A/P is an integral domain. (2) An ideal m in A is maximal if and only if A/ m is a field.

#### What are examples of ideals?

The definition of an ideal is a person or thing that is thought of as perfect for something. An example of ideal is a home with three bedrooms to house a family with two parents and two children. Ideal is defined as something or someone who is thought of as a perfect example of something.

Is every ideal a Subring?

An ideal must be closed under multiplication of an element in the ideal by any element in the ring. Since the ideal definition requires more multiplicative closure than the subring definition, every ideal is a subring.