### Zero Divisors

We just learned of homomorphisms, and zero divisors. How does knowing if an integer is one-to-one allow us to prove it to be a zero divisor?

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We just learned of homomorphisms, and zero divisors. How does knowing if an integer is one-to-one allow us to prove it to be a zero divisor?

(See attached file for full problem description) Z2 means modulo 2 and Z2n means modulo 2n.

(See attached file for full problem description) --- 1. Show that if is a ring homomorphism and A is an ideal of R Then need not be an ideal of S. (Compare with property "If A is an ideal and is onto S, then is an ideal).

Let A be a commutative ring with identity 1, and let A[x] be the ring of polynomials with coefficients in A. Let f (x) = a0+ a1x + ... + anxn! A[x] . Prove that f (x) is a zero - divisor in A[x] IF AND ONLY IF (iff) 7c ! A, c ! 0 " cf (x) = 0. Please see the attached file for the fully formatted problems.

If n Є R and R is a commutative ring we indicate by Mn(R) the ring of allnxn entries wrt the usual operations on matrices. If n>1 this ring is commutative even if R is. Let S={(aij)ЄMn(R)|i≠j=>aij=0} Let k be an integer 1≤k≤n. Show that a) S is a commutative subring of Mn(R) b) The function f: S

Let R be the set of all continuous functions from the set of real numbers into itself. Then R is a commutative ring with the following operations: (f+g)(x)=f(x) + g(x) and (fg)(x)=f(x)g(x) for all x. Now let I be the set of all functions f(x) an element of R such that f(1)=0. Show that I is a maximal ideal of R. Maximal

Show that N is contained in P for each prime ideal, P of a commutative ring R. Where N is the set of all nilpotent elements. "a" is nilpotent if a^n=0 for some positive integer n. N itself is an ideal.

See attached pdf file.

See attached pdf file. --- - Find all ring homomorphisms from Z... ---

Let . Show that the map the residue of a+ b modulo 2, is a ring homomorphism with . Prove that . Hence, or otherwise, give a maximal ideal of . Consider the ideal (2)+(x) of . Show that (2)+(x) . Hence explain why (x) is not a maximal ideal of . NOTE: All question marks are Z, the integers Please see the attached

Let . Prove that the map given by , where is the residue of a modulo n, is a ring homomorphism. Find the kernel and image of . Prove that if is a ring homomorphism, then given by is also a ring homomorphism. Write down two distinct maximal ideals of . Does have a finite or infinite number of maximal ideals?

(See attached file for full problem description with proper symbols) For part one....the first is in rational numbers, and second is in integers. --- ? Verify that is a sub field of and that is a sub ring of . ? Let R be a commutative ring and I an ideal of R. let and be elements of R. prove that is then

Give an example of a ring which is not a principle ideal domain.

Prove that a module over a polynomial ring C[t] is a finite dimensional vector space with a linear operator that plays the role of multiplication by t.

Prove that every cyclic module in a commutative ring R is of the form R/L for some ideal L. //Note: R/L is said "R modulo L"

(1) Given a ring R, an element e is called an idempotent if e^2 = e. (i) Let R1 and R2 be two commutative rings with unity. Consider R = R1 x R2. Find two non-zero idempotents e1,e2 E R such that 1= e1 + e2 and e1e2 = 0. (Be careful: what is 1 in this R? What is 0?) (ii) On the other hand, suppose R is any commutative ring wit

Note: Z is integer numbers C is set containment Here is the problem Let I be an ideal in a ring R. Define [ R : I ] = { r in R such that xr in R for all x in R } 1) Show that [ R : I ] is an ideal of R that contains I 2) If R is assumed to have a unity, what can you say about [ R : I ] ? 3) Find [ 2Z

1. Let R and S be commutative rings with unity, and let φ: R S be a ring homomorphism. If M is an S-module, prove that M is also an R-module if we define rm = φ(r)m for all r E R and m E M. 2. If M1 and M2 are submodules of an R-module M such that M = M1(+)M2, prove that M1 = M/M2 and M2 = M/M1.

An element a of a ring R with unity is von Neumann regular if there exists b such that aba = a. Show that the only element in Jacobson radical J[R] having this property is the zero element.

1. Let R be a ring. Prove that if x, y E R such that xy is right quasi-regular then yx is also right quasi-regular. 3. Let M and N be left R-modules. Let f : M N and g : N M be left R-module homomorphisms such that fg(y) = y for all y N. Show that M = ker(f) im(g). Please see attached.

For any x,y E R (i.e. Ring R) the following equalities hold. a) 0.x=0 b) a(-b)=(-a)b=-(ab) Prove either a or b. State any properties used in your proof. Please see attached for full question.

Let J and I be ideals of the ring R, with J C I C R. Show that J is an ideal in the ring I (Recall that any ideal of a ring is also a subring; so I is a ring in its own right) Note that: To show J an ideal of I, we must show that 1) it is an additive subgroup of R and 2) it is satisfied bJ C J and Jb C J

Let R commutative ring with unity, and S a sub monoid of the multiplicative monoid of R. In RxS define (a,b) ~ (b,t) if Эu є S э u(at-bs)= 0. Show that ~ is an equivalence relation in RxS. Denote the equivalence class of (a,s) as a/s and the quotient set consisting of these classes as RS-¹. Show that RS-¹ be

Let R be a ring with unity e, R' a set, η a bijective map from R' into R. show that R' becomes a ring with unity if one defines: a'+ b' = ηˉ¹ (η(a')+ η(b')) a' b' = ηˉ¹(η(a') η(b')) 0'= ηˉ¹(0) e'= ηˉ¹(e) and that is an isomorphism of R' with R. Use

Let phi be a homomorphism of a ring R with unity onto a nonzero ring R'. Let u be a unit in R. Show that phi (u) is a unit in R'.

I) Show that if D is an integral domain then D[x] is never a field. ii) Is the assumption "D is an integral domain" needed here? That is, does the conclusion hold if D is merely assumed to be a ring?

Let and be ideals of the ring and suppose I C J. Prove: The function phi : R/I --> R/J defined by phi(a+I)=a+J is a well-defined ring homomorphism that is also onto. Please see the attached file for the fully formatted problem.

Please see the attached file for the fully formatted problems. 1. Ler R be a ring, and , prove, using axioms for a ring, the following ? The identity element of R s unique ? That -r is the unique element of R such tht (-r)+r = 0. (hint, for part 1, suppose that 1 and 1' ate two identities of R, show that 1-1' must be

2. A domino is a 2x1 rectangular piece of wood. On each half of the domino is a number, denoted by dots. In the figure, we show all C(5,2) = 10 dominoes we can make where the numbers on the dominoes are all pairs of values chosen from {1,2,3,4,5} (we do not include dominoes where the two numbers are the same). Notice that we hav