Prompts Suomitted Answers Proposition: Let n be an integer. If n Sis odd, then nis Choose a match even. Proof Suppose that n+sis odd and nis also odd. By definition, then, there exists integers kand I so that n+5= 2k+1 and n= 21-1. Hence, we have 2k1=n+5 = (2- 17 -5 = 41-41-1+5 = 22 - 21- 31 Therefore, 2k+ 1seven. This is clearly impossible, and hence we cannot have that n +5is odd and nis also odd. Therefore, if that n²-sis odd, we must have nis even. Proposition: Let ab be integers. If ab is even, then at least Choose a match one of a orbis even. Proof Suppose that a and bare both odd. Then there are integers kand iso thata=2k+1 and b=21-1. Therefore, we have ab = (2k - 12- 1)= 4k+ 2k -2-1= 2zkl-k+-1, so ab is odd Thus, If ab is even, we must have at least one of a or bis Even. Proposition: Let a and b be integers. If a+bis even, then a Choose a match and bare either boch odd or bath even. Proof: Suppose that a and bare not both odd and nat both even, so that one of a and bis odd, and the other is even. Without lass of generality, suppose that a is odd andbis even. Then there are integers kand I such that a 2k 1 and b= 2L Therefore, a-b = (2k- 1)-21 = 2k +-1, so a+ bis odd. Hence, If a+ b is even, then a and bare either both odd or both even. Theorem: fa and bare consecutive integers, then the sum Choose a match a+bis odd. Proof Assume that a and bare consecutive integers. Assume also that the sum a-bis not odd. Because the suma-bis not odd, there exists no number k such that a+ b= 2k-1. However, the integers a and bare consecutive, so we may write the sum a -bas 20+ 1. Thus, we have derived that a bz k-1 for any integer kand also that a -b= 20-1. If we hoid that a andbare consecutive then we know that the sumab must be add. Theorem: The sum of an even integer and an odd integer is Choose a match odd. Proof: Suppose a is an even integer and bis an odd integer. Then, by our definitions of even and odd numbers, we know that integers mand n exist so that a 2m and b= 2n- 1. Then a+b= (2Zm) - (2n - 1)=2(m+n)+1=2c +1 where c= m-nis an integer by the closure property of addition. We have shown that a-b=2c-1 for an integer c so a-b must be odd.

College Algebra (MindTap Course List)
12th Edition
ISBN:9781305652231
Author:R. David Gustafson, Jeff Hughes
Publisher:R. David Gustafson, Jeff Hughes
Chapter8: Sequences, Series, And Probability
Section8.5: Mathematical Induction
Problem 42E
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Given the following theorem/statement and its proof, MATCH the Method of Proof used to prove the given theorem/statement. 

Prompes
Suomittea AnSwers
Proposition: Let n be an integer. If n+5is odd, then nis
Choose a match
Even.
Proof:
Suppose that n+5is odd and n is also odd. By definition,
then, there exists integers kand I so that n+5= 2k +1 and
n= 21- 1. Hence, we have 2k +1=n+5
= (2- 1 +5
= 41 + 41 -1+5
= 2(2 - 21+ 3).
Therefore, 2k +1 s even.
This is clearly impossible, and hence we cannot have that n 2
+5 is odd and n is also odd.
Therefore, if that n-5is odd, we must have n is even.
Proposition: Let a, b be integers. If ab is even, then at least
Choose a match
one of a orbis even.
Proof:
Suppose that a and bare both odd. Then there are integers
kand so thata= 2k+1 and b= 21- 1.
Therefore, we have ab = (2k - 12+ 1) = 4kd+ 2k - 21 +1=
2(2kl +k+)1, so ab is odd.
Thus, If ab is cven, we must have at least one of a or b is
Even.
Proposition: Let a and b be integers. If a +bis even, then a
Choose a match
and bare either both odd or bath even.
Proot:
Suppose that a and bare not both odd and not both even,
so that one of a and bis odd, and the other is even. Without
loss of generality, suppose that a is odd and bis even. Then
there are integers kand I such that a = 2k +1 and b= 2L
Therefore, a+b = (2k - 1) + 21 = 20+ )- 1, so a+bis odd.
Hence, If a+bis even, then a and bare either both odd or
both even.
Theorem: Ifa and b are consecutive integers, then the sum
a+bis odd.
Choose a match
Proof:
Assume that oa and bare consecutive integers. Assume also
that the sum a-bis not odd. Because the sum a-bis not
odd, there exists no number k such that a+ b = 2k - 1.
However, the integers a and b are consecutive, so we may
write the sum abas 20 + 1. Thus, we have derived that a+
bz k-1 for any integer kand also that a -b= 20 - 1. If we
hold that a and b are consecutive then we know that the
sum a +b must be odd.
Theorem: The sum of an even integer and an odd integer is
Choose a match
odd.
Proof:
Suppose a is an even integer andbis an odd integer.
Then, by our definitions of even and odd numbers, we know
that integers m and n exist so that a 2m and b= 2n + 1.
Then a +b= (2m) + (2n + 1) = 2(m + n) +1= 2c +1 where c=
m+nis an integer by the closure property of addition.
We have shown that ab 2c1 for an integer c so a-b
must be odd.
Transcribed Image Text:Prompes Suomittea AnSwers Proposition: Let n be an integer. If n+5is odd, then nis Choose a match Even. Proof: Suppose that n+5is odd and n is also odd. By definition, then, there exists integers kand I so that n+5= 2k +1 and n= 21- 1. Hence, we have 2k +1=n+5 = (2- 1 +5 = 41 + 41 -1+5 = 2(2 - 21+ 3). Therefore, 2k +1 s even. This is clearly impossible, and hence we cannot have that n 2 +5 is odd and n is also odd. Therefore, if that n-5is odd, we must have n is even. Proposition: Let a, b be integers. If ab is even, then at least Choose a match one of a orbis even. Proof: Suppose that a and bare both odd. Then there are integers kand so thata= 2k+1 and b= 21- 1. Therefore, we have ab = (2k - 12+ 1) = 4kd+ 2k - 21 +1= 2(2kl +k+)1, so ab is odd. Thus, If ab is cven, we must have at least one of a or b is Even. Proposition: Let a and b be integers. If a +bis even, then a Choose a match and bare either both odd or bath even. Proot: Suppose that a and bare not both odd and not both even, so that one of a and bis odd, and the other is even. Without loss of generality, suppose that a is odd and bis even. Then there are integers kand I such that a = 2k +1 and b= 2L Therefore, a+b = (2k - 1) + 21 = 20+ )- 1, so a+bis odd. Hence, If a+bis even, then a and bare either both odd or both even. Theorem: Ifa and b are consecutive integers, then the sum a+bis odd. Choose a match Proof: Assume that oa and bare consecutive integers. Assume also that the sum a-bis not odd. Because the sum a-bis not odd, there exists no number k such that a+ b = 2k - 1. However, the integers a and b are consecutive, so we may write the sum abas 20 + 1. Thus, we have derived that a+ bz k-1 for any integer kand also that a -b= 20 - 1. If we hold that a and b are consecutive then we know that the sum a +b must be odd. Theorem: The sum of an even integer and an odd integer is Choose a match odd. Proof: Suppose a is an even integer andbis an odd integer. Then, by our definitions of even and odd numbers, we know that integers m and n exist so that a 2m and b= 2n + 1. Then a +b= (2m) + (2n + 1) = 2(m + n) +1= 2c +1 where c= m+nis an integer by the closure property of addition. We have shown that ab 2c1 for an integer c so a-b must be odd.
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