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.
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] .
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.
Prove the theorem in the lecture:Euclidean Domains and UFD's
Let F be a field, and let p(x) in F[x]. Prove that (p(x)) is a
maximal ideal in F[x] if and only if p(x) is irreducible over
F.
Let k ⊂ K be an extension of fields (not necessarily
finite-dimensional). Suppose f, g ∈ k[x],
and f divides g in K[x] (that is, there exists h ∈ K[x] such
that g = fh. Show that f divides
g in k[x].
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]
(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...