Let E/F be a field extension. Let a,b be elements elements of E and algebraic over...

Let E/F be a field extension. Let a,b be elements elements of E and algebraic over F. Let m=[Q(a):Q] and n=[Q(b):Q]. Assume that gcd(m,n)=1. Determine the basis of Q(a,b) over Q.

Expert Solution

Colby Messinger answered 2 years ago

Theorem: Let K/F be a field extension and let a ∈ K be algebraic over F....

Theorem: Let K/F be a field extension and let a ∈ K be algebraic over F. If deg(mF,a(x)) = n, then 1. F[a] = F(a). 2. [F(a) : F] = n, and 3. {1, a, a2 , ..., an−1} is a basis for F(a).

Let E be an extension field of a finite field F, where F has q elements....

Let E be an extension field of a finite field F, where F has q elements. Let a in E be an element which is algebraic over F with degree n. Show that F(a) has q^n elements. Please provide an unique answer and motivate all steps carefully. I also prefer that the solution is provided as written notes.

Let E/F be an algebraic extension and let K and L be intermediate fields (i.e. F...

Let E/F be an algebraic extension and let K and L be intermediate fields (i.e. F ⊆ K ⊆ E and F ⊆ L ⊆ E). Assume that [K : F] and [L : F] are finite and that at least K/F or L/F is Galois. Prove that [KL : F] = [K : F][L : F] / [K ∩ L : F] .

Problem 3. Let F ⊆ E be a field extension. (i) Suppose α ∈ E is...

Problem 3. Let F ⊆ E be a field extension. (i) Suppose α ∈ E is algebraic of odd degree over F. Prove that F(α) = F(α^2 ). Hints: look at the tower of extensions F ⊆ F(α^2 ) ⊆ F(α) and their degrees. (ii) Let S be a (possibly infinite) subset of E. Assume that every element of S is algebraic over F. Prove that F(S) = F[S]

let E be a finite extension of a ﬁeld F of prime characteristic p, and let...

let E be a finite extension of a ﬁeld F of prime characteristic p, and let K = F(Ep) be the subﬁeld of E obtained from F by adjoining the pth powers of all elements of E. Show that F(Ep) consists of all ﬁnite linear combinations of elements in Ep with coeﬃcients in F.

Prove the following: (a) Let A be a ring and B be a field. Let f...

Prove the following: (a) Let A be a ring and B be a field. Let f : A → B be a surjective homomorphism from A to B. Then ker(f) is a maximal ideal. (b) If A/J is a field, then J is a maximal ideal.

7. Let E be a ﬁnite extension of the ﬁeld F of prime characteristic p. Show...

7. Let E be a ﬁnite extension of the ﬁeld F of prime characteristic p. Show that the extension is separable if and only if E = F(Ep).

(3) Let V be a vector space over a field F. Suppose that a ? F,...

(3) Let V be a vector space over a field F. Suppose that a ? F, v ? V and av = 0. Prove that a = 0 or v = 0. (4) Prove that for any field F, F is a vector space over F. (5) Prove that the set V = {a0 + a1x + a2x 2 + a3x 3 | a0, a1, a2, a3 ? R} of polynomials of degree ? 3 is a vector space over...

Let F be a field and let φ : F → F be a ring isomorphism....

Let F be a field and let φ : F → F be a ring isomorphism. Define Fix φ to be Fix φ = {a ∈ F | φ(a) = a}. That is, Fix φ is the set of all elements of F that are fixed under φ. Prove that Fix φ is a field. (b) Define φ : C → C by φ(a + bi) = a − bi. Take for granted that φ is a ring isomorphism (we...

Let (F, <) be an ordered field, let S be a nonempty subset of F, let...

Let (F, <) be an ordered field, let S be a nonempty subset of F, let c ∈ F, and for purposes of this problem let cS = {cx | x ∈ S}. (Do not use this notation outside this problem without defining what you mean by the notation.) Assume that c > 0. (i) Show that an element b ∈ F is an upper bound for S if and only if cb is an upper bound for cS. (ii)...

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