5.104. Let p and q be irreducible elements of a PID R. Prove that R/(pq) =...
Let P, Q ∈ Z[x]. Prove that P and Q are relatively prime in Q[x] if and only if the ideal (P, Q) of Z[x] generated by P and Q contains a non-zero integer (i.e. Z ∩ (P, Q) ̸= {0}). Here (P, Q) is the smallest ideal of Z[x] containing P and Q, (P, Q) := {αP + βQ|α, β ∈ Z[x]}. (iii) For which primes p and which integers n ≥ 1 is the polynomial xn − p...
Let P and Q be two projectors, such that PQ zQP prove that (PQ) is a projector and (a) CLPQ) = c(p). ndo) (6) Null (PQ) = Null P + Null Q
(1) Prove that if R is a PID and P is a prime ideal, then R/P is another PID Show that if I is an arbitrary ideal, then R/I might not be a PID (2) Find an expression for the ged and lem of a pair of nonzero elements a, b in a UFD, and prove that it is correct. (1) Prove that if R is a PID and P is a prime ideal, then R/P is another PID Show...
4. (a) Prove that if f(x) E Q[x] is irreducible in R[x], then it is irreducible in Q[x]. Is the converse of this statement true? Explain why or why not. (b) Prove that if f(x) E Q[x] is reducible in Q[x], then it is reducible in R[x]. Is the converse of this statement true? Explain why or why not.
Part D,E,F,G 10. Let p(x) +1. Let E be the splitting field for p(x) over Q. a. Find the resolvent cubic R(z). b. Prove that R(x) is irreducible over Q. c. Prove that (E:Q) 12 or 24. d. Prove: Gal(E/Q) A4 or S4 e. If p(x) (2+ az+ b)(a2 + cr + d), verify the calculations on page 100 which show that a2 is a root of the cubic polynomial r(x)3-4. 1. f. Prove: r(x) -4z 1 is irreducible in...
Let R be a UFD, and let So be a set of irreducibles in R. Let S := {ufi.fr: k > 0,[1,...,SE E So, u € R*} (we use the convention that the product fifk is 1 when k=0). (a) Show that S is multiplicatively closed. (b) Suppose / ER, GES. Show that is a unit in S-R if and only if SES. (c) Show that res-'R is irreducible if and only if x is associates with y = {es-R,...
Let k be a field of positive characteristic p, and let f(x)be an irreducible polynomial. Prove that there exist an integer d and a separable irreducible polynomial fsep (2) such that f(0) = fsep (2P). The number p is called the inseparable degree of f(c). If f(1) is the minimal polynomial of an algebraic element a, the inseparable degree of a is defined to be the inseparable degree of f(1). Prove that a is inseparable if and only if its...
2. (10) Let p be an odd prime. Let f(x) E Q(x) be an irreducible polynomial of degree p whose Galois group is the dihedral group D2p of a regular p-gon. Prove that f(x) has either all real roots precisely one real root or 2. (10) Let p be an odd prime. Let f(x) E Q(x) be an irreducible polynomial of degree p whose Galois group is the dihedral group D2p of a regular p-gon. Prove that f(x) has either...
Let p be an odd prime. Let f(x) ∈ Q(x) be an irreducible polynomial of degree p whose Galois group is the dihedral group D_2p of a regular p-gon. Prove that f (x) has either all real roots or precisely one real root.
3. Prove that p(x) = 3x3 + 22x2 + 38x + 34 is irreducible in Q[x].