7. Let R be a commutative ring and let F = F(R, R) be the set of functions f: R→ R. Functions in F can be added and multiplied pointwise using the operations from R, i.e. define (f+ 9)(z) = f(x) + g(x) (f9)(z) = f(r)g(x) (a) Prove F is a commutative ring.

Elements Of Modern Algebra
8th Edition
ISBN:9781285463230
Author:Gilbert, Linda, Jimmie
Publisher:Gilbert, Linda, Jimmie
Chapter8: Polynomials
Section8.1: Polynomials Over A Ring
Problem 3E
icon
Related questions
Question
7. Let R be a commutative ring and let F = F(R, R) be the set of functions f : R R. Functions
in F can be added and multiplied pointwise using the operations from R, i.e. define
(S + 9)(x) = f(x) + g(x)
(f9)(2) = f(a)g(x)
(a) Prove F is a commutative ring.
(b) Let I denote the identity function 1(r) = r in F. Prove that the map p : R[X] → F
given by
p(a, X" +. + a1 X + ao) = a," + . + a1l + ao
...
is a ring homomorphism, where R[X] is the ring of polynomials with coefficients in R.
1 of 2
MATH 4107: Homework 10
(c) Give an example showing that p is in general not injective (hint: try R= Z/2Z). Find
ker(p) when R = Z/pZ where p is prime. Note that the fact that p is not injective means
that one cannot in general view polynomials in R[X] as R-valued functions on R, which
is in sharp contrast to the case of Z[X], R[X], or C[X].
Transcribed Image Text:7. Let R be a commutative ring and let F = F(R, R) be the set of functions f : R R. Functions in F can be added and multiplied pointwise using the operations from R, i.e. define (S + 9)(x) = f(x) + g(x) (f9)(2) = f(a)g(x) (a) Prove F is a commutative ring. (b) Let I denote the identity function 1(r) = r in F. Prove that the map p : R[X] → F given by p(a, X" +. + a1 X + ao) = a," + . + a1l + ao ... is a ring homomorphism, where R[X] is the ring of polynomials with coefficients in R. 1 of 2 MATH 4107: Homework 10 (c) Give an example showing that p is in general not injective (hint: try R= Z/2Z). Find ker(p) when R = Z/pZ where p is prime. Note that the fact that p is not injective means that one cannot in general view polynomials in R[X] as R-valued functions on R, which is in sharp contrast to the case of Z[X], R[X], or C[X].
Expert Solution
steps

Step by step

Solved in 4 steps

Blurred answer
Knowledge Booster
Ring
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, advanced-math and related others by exploring similar questions and additional content below.
Recommended textbooks for you
Elements Of Modern Algebra
Elements Of Modern Algebra
Algebra
ISBN:
9781285463230
Author:
Gilbert, Linda, Jimmie
Publisher:
Cengage Learning,
Algebra & Trigonometry with Analytic Geometry
Algebra & Trigonometry with Analytic Geometry
Algebra
ISBN:
9781133382119
Author:
Swokowski
Publisher:
Cengage
Trigonometry (MindTap Course List)
Trigonometry (MindTap Course List)
Trigonometry
ISBN:
9781337278461
Author:
Ron Larson
Publisher:
Cengage Learning
Linear Algebra: A Modern Introduction
Linear Algebra: A Modern Introduction
Algebra
ISBN:
9781285463247
Author:
David Poole
Publisher:
Cengage Learning