Homework Answers
27. (a) Let m and n be integers > 1 which are relatively prime. Show that the map f : Z → Z/mZ × ...
27. (a) Let m and n be integers > 1 which are relatively prime. Show that the map f : Z → Z/mZ × Z/nZ whith f(x) = (x + mZ, x + nZ) is surjective (b) Prove the Chinese Remainder Theorem: If m and n are relatively prime integers > 1 and if a and b are any integers, then there exists a E Z such that b(mod n). a(mod m) and a a Hint: (a)]
27. (a) Let...
Let p be an odd prime. Prove that if g is a primitive root modulo p, then g^(p-1)/2 ≡ -1 (mod p).
Let
p be an odd prime. Prove that if g is a primitive root modulo p,
then g^(p-1)/2 ≡ -1 (mod p).
Let p be an odd prime. Prove that if g is a primitive root modulo p, then go-1)/2 =-1 (mod p) Hint: Use Lemma 2 from Chapter 28 (If p is prime and d(p 1), then cd-1 Ξ 0 (mod p) has exactly d solutions).
Let p be an odd prime. Prove that if g is a primitive...
Problem 7. Let M = 2" – 1, where n is an odd prime. Let p...
Problem 7. Let M = 2" – 1, where n is an odd prime. Let p be any prime factor of M. Prove that p=n·2j + 1 for some positive integer j.
Let m be a positive integer and let a and b be integers relatively prime to m with (ord m a , ord...
Let m be a positive integer and let a and b be integers relatively prime to m with (ord m a , ord m b) )=1. Prove that ord m (ab)= (ord m a) (ord m b) (Hint: Let k=ord m(a),l=ord m(b), and n=ord m(ab). Then 1≡(ab)^kn≡b^kn mod m. What does this imply about l in relation to kn?
(4) Let p Z be a prime. Prove that zli/(p+1) has exactly ] p2 +1 elements. Use that 5+5i (2+i)(3+...
(4) Let p Z be a prime. Prove that zli/(p+1) has exactly ] p2 +1 elements. Use that 5+5i (2+i)(3+i) to determine how many elements Zu/5+5i) has. (5) Let m,n be integers with m|n. Prove that the surjective ring homomor- phism Z/n -> Z/m induces a group homomorphism on units, and that this group homomorphism is also surjective.
(4) Let p Z be a prime. Prove that zli/(p+1) has exactly ] p2 +1 elements. Use that 5+5i (2+i)(3+i) to determine...
Write your own answers 10. Let p be a prime number, and let a be an...
Write your own answers
10. Let p be a prime number, and let a be an integer that is not divisible by p. Prove that the congruence equation ax = 1 mod p has a solution X e Z.
Fact: If d > 2 is an integer, then there exists a prime q such that...
Fact: If d > 2 is an integer, then there exists a prime q such that q divides d. (1) Let e and f be positive integers. Prove that if ged(e, f) = 1, then god(e?,f) = 1. (2) Let m be a positive integer. Prove that if m is rational, then m is an integer.
3 Let p and q be prime numbers and let G be a non-cyclic group of...
3 Let p and q be prime numbers and let G be a non-cyclic group of order pq. Let H be a subgroup of G.Show that either H is cyclic or H-G. 12 - Let I and J, be ideals in R. In, the homomorphismJ f: (!+J a → a+J use the First Isomorphism Theorem to prove that I+J
Let P, Q ∈ Z[x]. Prove that P and Q are relatively prime in Q[x] if...
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 n be a nonnegative integer and let F 22 + 1 be a Fermat number. Prove that if is a prime nu...
Let n be a nonnegative integer and let F 22 + 1 be a Fermat number. Prove that if is a prime number, then either n=0 or 3--1mod F. [Hint: If n 2 1, use the law of quadratic reciprocity to evaluate the Legendre symbol (3/F). Now use Euler's Criterion (Theorem 4.4).]
Let n be a nonnegative integer and let F 22 + 1 be a Fermat number.
Prove that if is a prime number, then either n=0 or 3--1mod...
27. (a) Let m and n be integers > 1 which are relatively prime. Show that the map f : Z → Z/mZ × Z/nZ whith f(x) = (x + mZ, x + nZ) is surjective (b) Prove the Chinese Remainder Theorem: If m and n are relatively prime integers > 1 and if a and b are any integers, then there exists a E Z such that b(mod n). a(mod m) and a a Hint: (a)]
27. (a) Let...
Let
p be an odd prime. Prove that if g is a primitive root modulo p,
then g^(p-1)/2 ≡ -1 (mod p).
Let p be an odd prime. Prove that if g is a primitive root modulo p, then go-1)/2 =-1 (mod p) Hint: Use Lemma 2 from Chapter 28 (If p is prime and d(p 1), then cd-1 Ξ 0 (mod p) has exactly d solutions).
Let p be an odd prime. Prove that if g is a primitive...
Problem 7. Let M = 2" – 1, where n is an odd prime. Let p be any prime factor of M. Prove that p=n·2j + 1 for some positive integer j.
(4) Let p Z be a prime. Prove that zli/(p+1) has exactly ] p2 +1 elements. Use that 5+5i (2+i)(3+i) to determine how many elements Zu/5+5i) has. (5) Let m,n be integers with m|n. Prove that the surjective ring homomor- phism Z/n -> Z/m induces a group homomorphism on units, and that this group homomorphism is also surjective.
(4) Let p Z be a prime. Prove that zli/(p+1) has exactly ] p2 +1 elements. Use that 5+5i (2+i)(3+i) to determine...
Write your own answers
10. Let p be a prime number, and let a be an integer that is not divisible by p. Prove that the congruence equation ax = 1 mod p has a solution X e Z.
Fact: If d > 2 is an integer, then there exists a prime q such that q divides d. (1) Let e and f be positive integers. Prove that if ged(e, f) = 1, then god(e?,f) = 1. (2) Let m be a positive integer. Prove that if m is rational, then m is an integer.
3 Let p and q be prime numbers and let G be a non-cyclic group of order pq. Let H be a subgroup of G.Show that either H is cyclic or H-G. 12 - Let I and J, be ideals in R. In, the homomorphismJ f: (!+J a → a+J use the First Isomorphism Theorem to prove that I+J
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 n be a nonnegative integer and let F 22 + 1 be a Fermat number. Prove that if is a prime number, then either n=0 or 3--1mod F. [Hint: If n 2 1, use the law of quadratic reciprocity to evaluate the Legendre symbol (3/F). Now use Euler's Criterion (Theorem 4.4).]
Let n be a nonnegative integer and let F 22 + 1 be a Fermat number.
Prove that if is a prime number, then either n=0 or 3--1mod...
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