Let F be a finite field. Prove that there exists an integer n≥1,
such that n.1_F = 0_F .
Show further that the smallest positive integer with this
property is a prime number.
Let G be a cyclic group generated by an element a.
a) Prove that if an = e for some n ∈ Z, then G is
finite.
b) Prove that if G is an infinite cyclic group then it contains
no nontrivial finite subgroups. (Hint: use part (a))
Let F be a field.
(a) Prove that the polynomials a(x, y) = x^2 − y^2, b(x, y) =
2xy and c(x, y) = x^2 + y^2 in F[x, y] form a Pythagorean triple.
That is, a^2 + b^2 = c^2. Use this fact to explain how to generate
right triangles with integer side lengths.
(b) Prove that the polynomials a(x,y) = x^2 − y^2, b(x,y) = 2xy
− y^2 and c(x,y) = x^2 − xy + y2 in F[x,y]...
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 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.
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.
2 Let F be a field and let R = F[x, y] be the ring of
polynomials in two variables with coefficients in F.
(a) Prove that
ev(0,0) : F[x, y] → F
p(x, y) → p(0, 0)
is a surjective ring homomorphism.
(b) Prove that ker ev(0,0) is equal to the ideal (x, y) = {xr(x,
y) + ys(x, y) | r,s ∈ F[x, y]}
(c) Use the first isomorphism theorem to prove that (x, y) ⊆
F[x, y]...