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Discrete Mathematics With Applicat...

5th Edition
EPP + 1 other
ISBN: 9781337694193

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BuyFindarrow_forward

Discrete Mathematics With Applicat...

5th Edition
EPP + 1 other
ISBN: 9781337694193
Textbook Problem
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In Example 8.3.12, define operations of addition (+) and multiplication (·) as follows: For every
( a , b ) , ( c , d ) A , [ ( a , b ) ] + [ ( c , d ) ] = [ ( a d + b c , b d ) ] [ ( a , b ) ] [ ( c , d ) ] = [ ( a c , b d ) ] .

a. Prove that this addition is well defined. That is, show that if [ ( a , b ) ] = [ ( a ' , b ' ) ] and [ ( c , d ) ] = [ ( c ' , d ' ) ] , then [ ( a d + b c , b d ) ] = [ ( a ' d ' + b ' c ' , b ' d ' ) ] .
b. Prove that this multiplication is well defined. That is, show that if [ ( a , b ) ] = [ ( a ' , b ' ) ] and [ ( c , d ) ] = [ ( c ' , d ' ) ] . then [ ( a c + b d ) ] = [ ( a ' c ' , b ' d ' ) ] .
c. Show that [(0, 1)] is an identity element for addition. That is, show that for any ( a , b ) A , [ ( a , b ) ] + [ ( 0 , 1 ) ] = [ ( 0 , 1 ) ] + [ ( a , b ) ] = [ ( a , b ) ] .
d. Find an identity element for multiplication. That is, find (i, j) in A so that for every (a, b) in A , [ ( a , b ) ] [ ( i , j ) ] = [ ( i , j ) ] [ ( a , b ) ] = [ ( a , b ) ] .
e. For any ( a , b ) A , show that [(-a, b)] is an inverse for [ ( a , b ) ] for addition. That is, show that [ ( a , b ) ] + [ ( a , b ) ] = [ ( a , b ) ] + [ ( a , b ) ] = [ ( 0 , 1 ) ] .
f. Given any ( a , b ) A with a 0 , find an inverse for [ ( a , b ) ] for multiplication. That is, find (c, d) in A so that [ ( a , b ) ] [ ( c , d ) ] = [ ( c , d ) ] [ ( a , b ) ] = [ ( i , j ) ] . where [ ( i , j ) ] is the
identity element you found in part (d).

To determine

(a)

To show that if [(a,b)]=[(a,b)] and [(c,d)]=[(c,d)], then

[(ad+bc,bd)]=[(ad+bc,bd)].

Explanation

Given information:

The operations of addition (+)and multiplication (·) as follows: For all (a,b),(c,d)A,

[(a,b)]+[(c,d)]=[(ad+bc,bd)] [(a, b)][(c, d)]=[(ac, bd)]

Proof:

A=Z×(Z{0})R={(( a,b),( c,d))A×A|ad=bc}

[(a,b)]+[(c,d)]=[(ad+bc,bd)][(a,b)][(c,d)]=[(ac,bd)]

Let us assume that [(a,b)]=[(a,b)] and

[(c,d)]=[(c,d)].

In general: a[a] for all aA:

(a,b)[(a,b)]=[(a',b')](c,d)[(c,d)]=[(c',d')]

By the definition of the equivalence class:

To determine

(b)

To prove:

If [(a,b)]=[(a',b')] and [(c,d)]=[(c',d')], then [(ac,bd)]=[(a'c',b'd')].

To determine

(c)

To show that [(0,1)] is an identity element for addition. That is, show that for any (a,b)A,

[(a,b)]+[(0,1)]=[(0,1)]+[(a,b)]=[(a,b)].

To determine

(d)

An identity element for multiplication for the given operation. That means, find (i,f) in A so that for all (a,b) in A. [(a,b)][(i,j)]=[(i,j)][(a,b)]=[(a,b)].

To determine

(e)

To prove:

To show that [(a,b)] is an inverse for [(a,b)] for addition if (a,b)A,. That means, to show that [(a,b)]+[(a,b)]=[(a,b)]+[(a,b)]=[(0,1)].

To determine

(f)

An inverse for [(a,b)] for multiplication for any (a,b)A with a0. That means, to find (c,d) in A so that [(a,b)][(c,d)]=[(c,d)][(a,b)]=[(i,j)], where [(i,j)] is the identity element you found in part (d).

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Sect-8.1 P-6ESSect-8.1 P-7ESSect-8.1 P-8ESSect-8.1 P-9ESSect-8.1 P-10ESSect-8.1 P-11ESSect-8.1 P-12ESSect-8.1 P-13ESSect-8.1 P-14ESSect-8.1 P-15ESSect-8.1 P-16ESSect-8.1 P-17ESSect-8.1 P-18ESSect-8.1 P-19ESSect-8.1 P-20ESSect-8.1 P-21ESSect-8.1 P-22ESSect-8.1 P-23ESSect-8.1 P-24ESSect-8.2 P-1TYSect-8.2 P-2TYSect-8.2 P-3TYSect-8.2 P-4TYSect-8.2 P-5TYSect-8.2 P-6TYSect-8.2 P-7TYSect-8.2 P-8TYSect-8.2 P-9TYSect-8.2 P-10TYSect-8.2 P-1ESSect-8.2 P-2ESSect-8.2 P-3ESSect-8.2 P-4ESSect-8.2 P-5ESSect-8.2 P-6ESSect-8.2 P-7ESSect-8.2 P-8ESSect-8.2 P-9ESSect-8.2 P-10ESSect-8.2 P-11ESSect-8.2 P-12ESSect-8.2 P-13ESSect-8.2 P-14ESSect-8.2 P-15ESSect-8.2 P-16ESSect-8.2 P-17ESSect-8.2 P-18ESSect-8.2 P-19ESSect-8.2 P-20ESSect-8.2 P-21ESSect-8.2 P-22ESSect-8.2 P-23ESSect-8.2 P-24ESSect-8.2 P-25ESSect-8.2 P-26ESSect-8.2 P-27ESSect-8.2 P-28ESSect-8.2 P-29ESSect-8.2 P-30ESSect-8.2 P-31ESSect-8.2 P-32ESSect-8.2 P-33ESSect-8.2 P-34ESSect-8.2 P-35ESSect-8.2 P-36ESSect-8.2 P-37ESSect-8.2 P-38ESSect-8.2 P-39ESSect-8.2 P-40ESSect-8.2 P-41ESSect-8.2 P-42ESSect-8.2 P-43ESSect-8.2 P-44ESSect-8.2 P-45ESSect-8.2 P-46ESSect-8.2 P-47ESSect-8.2 P-48ESSect-8.2 P-49ESSect-8.2 P-50ESSect-8.2 P-51ESSect-8.2 P-52ESSect-8.2 P-53ESSect-8.2 P-54ESSect-8.2 P-55ESSect-8.2 P-56ESSect-8.3 P-1TYSect-8.3 P-2TYSect-8.3 P-3TYSect-8.3 P-4TYSect-8.3 P-5TYSect-8.3 P-6TYSect-8.3 P-1ESSect-8.3 P-2ESSect-8.3 P-3ESSect-8.3 P-4ESSect-8.3 P-5ESSect-8.3 P-6ESSect-8.3 P-7ESSect-8.3 P-8ESSect-8.3 P-9ESSect-8.3 P-10ESSect-8.3 P-11ESSect-8.3 P-12ESSect-8.3 P-13ESSect-8.3 P-14ESSect-8.3 P-15ESSect-8.3 P-16ESSect-8.3 P-17ESSect-8.3 P-18ESSect-8.3 P-19ESSect-8.3 P-20ESSect-8.3 P-21ESSect-8.3 P-22ESSect-8.3 P-23ESSect-8.3 P-24ESSect-8.3 P-25ESSect-8.3 P-26ESSect-8.3 P-27ESSect-8.3 P-28ESSect-8.3 P-29ESSect-8.3 P-30ESSect-8.3 P-31ESSect-8.3 P-32ESSect-8.3 P-33ESSect-8.3 P-34ESSect-8.3 P-35ESSect-8.3 P-36ESSect-8.3 P-37ESSect-8.3 P-38ESSect-8.3 P-39ESSect-8.3 P-40ESSect-8.3 P-41ESSect-8.3 P-42ESSect-8.3 P-43ESSect-8.3 P-44ESSect-8.3 P-45ESSect-8.3 P-46ESSect-8.3 P-47ESSect-8.4 P-1TYSect-8.4 P-2TYSect-8.4 P-3TYSect-8.4 P-4TYSect-8.4 P-5TYSect-8.4 P-6TYSect-8.4 P-7TYSect-8.4 P-8TYSect-8.4 P-9TYSect-8.4 P-10TYSect-8.4 P-1ESSect-8.4 P-2ESSect-8.4 P-3ESSect-8.4 P-4ESSect-8.4 P-5ESSect-8.4 P-6ESSect-8.4 P-7ESSect-8.4 P-8ESSect-8.4 P-9ESSect-8.4 P-10ESSect-8.4 P-11ESSect-8.4 P-12ESSect-8.4 P-13ESSect-8.4 P-14ESSect-8.4 P-15ESSect-8.4 P-16ESSect-8.4 P-17ESSect-8.4 P-18ESSect-8.4 P-19ESSect-8.4 P-20ESSect-8.4 P-21ESSect-8.4 P-22ESSect-8.4 P-23ESSect-8.4 P-24ESSect-8.4 P-25ESSect-8.4 P-26ESSect-8.4 P-27ESSect-8.4 P-28ESSect-8.4 P-29ESSect-8.4 P-30ESSect-8.4 P-31ESSect-8.4 P-32ESSect-8.4 P-33ESSect-8.4 P-34ESSect-8.4 P-35ESSect-8.4 P-36ESSect-8.4 P-37ESSect-8.4 P-38ESSect-8.4 P-39ESSect-8.4 P-40ESSect-8.4 P-41ESSect-8.4 P-42ESSect-8.4 P-43ESSect-8.5 P-1TYSect-8.5 P-2TYSect-8.5 P-3TYSect-8.5 P-4TYSect-8.5 P-5TYSect-8.5 P-6TYSect-8.5 P-7TYSect-8.5 P-8TYSect-8.5 P-9TYSect-8.5 P-10TYSect-8.5 P-1ESSect-8.5 P-2ESSect-8.5 P-3ESSect-8.5 P-4ESSect-8.5 P-5ESSect-8.5 P-6ESSect-8.5 P-7ESSect-8.5 P-8ESSect-8.5 P-9ESSect-8.5 P-10ESSect-8.5 P-11ESSect-8.5 P-12ESSect-8.5 P-13ESSect-8.5 P-14ESSect-8.5 P-15ESSect-8.5 P-16ESSect-8.5 P-17ESSect-8.5 P-18ESSect-8.5 P-19ESSect-8.5 P-20ESSect-8.5 P-21ESSect-8.5 P-22ESSect-8.5 P-23ESSect-8.5 P-24ESSect-8.5 P-25ESSect-8.5 P-26ESSect-8.5 P-27ESSect-8.5 P-28ESSect-8.5 P-29ESSect-8.5 P-30ESSect-8.5 P-31ESSect-8.5 P-32ESSect-8.5 P-33ESSect-8.5 P-34ESSect-8.5 P-35ESSect-8.5 P-36ESSect-8.5 P-37ESSect-8.5 P-38ESSect-8.5 P-39ESSect-8.5 P-40ESSect-8.5 P-41ESSect-8.5 P-42ESSect-8.5 P-43ESSect-8.5 P-44ESSect-8.5 P-45ESSect-8.5 P-46ESSect-8.5 P-47ESSect-8.5 P-48ESSect-8.5 P-49ESSect-8.5 P-50ESSect-8.5 P-51ES