math e mati cs adv ance d mat 3 1 0 br i dge to

122
MAT 310 BRIDGE TO ADVANCED MATHEMATICS Richard Hammack Virginia Commonwealth University

Upload: others

Post on 15-May-2022

2 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: MATH E MATI CS ADV ANCE D MAT 3 1 0 BR I DGE TO

MAT 310 BRIDGE TO ADVANCED MATHEMATICS

Richard HammackVirginia Commonwealth University

Page 2: MATH E MATI CS ADV ANCE D MAT 3 1 0 BR I DGE TO

Virginia Commonwealth University

MAT 310 Bridge to Advanced Mathematics

Richard Hammack

Page 3: MATH E MATI CS ADV ANCE D MAT 3 1 0 BR I DGE TO

This text is disseminated via the Open Education Resource (OER) LibreTexts Project (https://LibreTexts.org) and like the hundredsof other texts available within this powerful platform, it is freely available for reading, printing and "consuming." Most, but not all,pages in the library have licenses that may allow individuals to make changes, save, and print this book. Carefullyconsult the applicable license(s) before pursuing such effects.

Instructors can adopt existing LibreTexts texts or Remix them to quickly build course-specific resources to meet the needs of theirstudents. Unlike traditional textbooks, LibreTexts’ web based origins allow powerful integration of advanced features and newtechnologies to support learning.

The LibreTexts mission is to unite students, faculty and scholars in a cooperative effort to develop an easy-to-use online platformfor the construction, customization, and dissemination of OER content to reduce the burdens of unreasonable textbook costs to ourstudents and society. The LibreTexts project is a multi-institutional collaborative venture to develop the next generation of open-access texts to improve postsecondary education at all levels of higher learning by developing an Open Access Resourceenvironment. The project currently consists of 14 independently operating and interconnected libraries that are constantly beingoptimized by students, faculty, and outside experts to supplant conventional paper-based books. These free textbook alternatives areorganized within a central environment that is both vertically (from advance to basic level) and horizontally (across different fields)integrated.

The LibreTexts libraries are Powered by MindTouch and are supported by the Department of Education Open Textbook PilotProject, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning SolutionsProgram, and Merlot. This material is based upon work supported by the National Science Foundation under Grant No. 1246120,1525057, and 1413739. Unless otherwise noted, LibreTexts content is licensed by CC BY-NC-SA 3.0.

Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do notnecessarily reflect the views of the National Science Foundation nor the US Department of Education.

Have questions or comments? For information about adoptions or adaptions contact [email protected]. More information on ouractivities can be found via Facebook (https://facebook.com/Libretexts), Twitter (https://twitter.com/libretexts), or our blog(http://Blog.Libretexts.org).

This text was compiled on 05/04/2022

®

Page 4: MATH E MATI CS ADV ANCE D MAT 3 1 0 BR I DGE TO

1 5/4/2022

TABLE OF CONTENTS

This book will initiate you into an esoteric world. You will learn and apply the methods of thought that mathematicians use toverify theorems, explore mathematical truth and create new mathematical theories. This will prepare you for advanced mathematicscourses, for you will be better able to understand proofs, write your own proofs and think critically and inquisitively aboutmathematics.

1: Sets

1.1: Introduction to Sets1.2: The Cartesian Product1.3: Subsets1.4: Power Sets1.5: Union, Intersection, Difference1.6: Complement1.7: Venn Diagrams1.8: Indexed Sets1.8: Sets That Are Number Systems1.9: Russell’s Paradox

2: Logic

2.0: Statement2.1: And, Or, Not2.2: Conditional Statements2.3: Biconditional Statements2.4: Truth Tables for Statements2.5: Logical Equivalence2.6: Quantifiers2.7: More on Conditional Statements2.8: Translating English to Symbolic Logic2.9: Negating Statements2.10: Logical Inference2.11: An Important Note

3: Counting

3.0: Lists3.1: The Multiplication Principle3.2: The Addition and Subtraction Principles3.3: Factorials and Permutations3.4: Counting Subsets3.5: Pascal’s Triangle and the Binomial Theorem3.6: The Inclusion-Exclusion Principle3.7: Counting Multisets3.8: New Page3.9: New Page

Page 5: MATH E MATI CS ADV ANCE D MAT 3 1 0 BR I DGE TO

2 5/4/2022

4: Direct Proof

4.1: Section 1-4.2: Section 2-4.3: Section 3-4.4: Section 4-4.5: Section 5-4.6: Section 6-Exercises

5: Contrapositive Proof

5.1: Section 1-5.2: Section 2-5.3: Section 3-5.4: Section 4-5.5: Section 5-5.6: Section 6-

6: Proof by Contradiction

6.0: Section 1-6.1: Section 2-6.2: Section 3-6.3: Section 4-6.4: Section 5-6.5: Section 6-

7: Proving Non-Conditional Statements

7.0: Section 1-7.1: Section 2-7.2: Section 3-7.3: Section 4-7.4: Section 5-7.5: Section 6-

8: Proofs Involving Sets

8.0: Section 1-8.1: Section 2-8.2: Section 3-8.3: Section 4-

9: Disproof

9.0: Section 1-9.1: Section 2-9.2: Section 3-9.3: Section 4-9.4: Section 5-9.5: Section 6-

Page 6: MATH E MATI CS ADV ANCE D MAT 3 1 0 BR I DGE TO

3 5/4/2022

10: Mathematical Induction

10.0: Section 1-10.1: Section 2-10.2: Section 3-10.3: Section 4-10.4: Section 5-10.5: Section 6-

11: Relations

11.0: Section 1-11.1: Section 2-11.2: Section 3-11.3: Section 4-11.4: Section 5-11.5: Section 6-

12: Functions

12.0: Section 1-12.1: Section 2-12.2: Section 3-12.3: Section 4-12.4: Section 5-12.5: Section 6-

13: Proofs in Calculus

13.0: Section 1-13.1: Section 2-13.2: Section 3-13.3: Section 4-13.4: Section 5-13.5: Section 6-

14: Cardinality of Sets

14.0: Section 1-14.1: Section 2-14.2: Section 3-14.3: Section 4-14.4: Section 5-14.5: Section 6-

Index

Glossary

Thumbnail: P. Oxy. 29, one of the oldest surviving fragments of Euclid's Elements, a textbook used for millennia to teach proof-writing techniques. The diagram accompanies Book II, Proposition 5. (Public Domain). Text from Oscar Levin's DiscreteMathematics text (CC BY-SA).

Page 7: MATH E MATI CS ADV ANCE D MAT 3 1 0 BR I DGE TO

4 5/4/2022

MAT 310 Bridge to Advanced Mathematics is shared under a CC BY-NC-ND license and was authored, remixed, and/or curated by RichardHammack.

Page 8: MATH E MATI CS ADV ANCE D MAT 3 1 0 BR I DGE TO

1 5/4/2022

CHAPTER OVERVIEW

1: Sets1.1: Introduction to Sets1.2: The Cartesian Product1.3: Subsets1.4: Power Sets1.5: Union, Intersection, Difference1.6: Complement1.7: Venn Diagrams1.8: Indexed Sets1.8: Sets That Are Number Systems1.9: Russell’s Paradox

1: Sets is shared under a CC BY-NC-ND license and was authored, remixed, and/or curated by Richard Hammack.

Page 19: MATH E MATI CS ADV ANCE D MAT 3 1 0 BR I DGE TO

1 5/4/2022

CHAPTER OVERVIEW

2: Logic2.0: Statement2.1: And, Or, Not2.2: Conditional Statements2.3: Biconditional Statements2.4: Truth Tables for Statements2.5: Logical Equivalence2.6: Quantifiers2.7: More on Conditional Statements2.8: Translating English to Symbolic Logic2.9: Negating Statements2.10: Logical Inference2.11: An Important Note

2: Logic is shared under a CC BY-NC-ND license and was authored, remixed, and/or curated by Richard Hammack.

Page 32: MATH E MATI CS ADV ANCE D MAT 3 1 0 BR I DGE TO

1 5/4/2022

CHAPTER OVERVIEW

3: Counting3.0: Lists3.1: The Multiplication Principle3.2: The Addition and Subtraction Principles3.3: Factorials and Permutations3.4: Counting Subsets3.5: Pascal’s Triangle and the Binomial Theorem3.6: The Inclusion-Exclusion Principle3.7: Counting Multisets3.8: New Page3.9: New Page

3: Counting is shared under a CC BY-NC-ND license and was authored, remixed, and/or curated by Richard Hammack.

Page 38: MATH E MATI CS ADV ANCE D MAT 3 1 0 BR I DGE TO

Richard Hammack 3.5.1 5/4/2022 https://math.libretexts.org/@go/page/33701

3.5: Pascal’s Triangle and the Binomial Theorem

3.5: Pascal’s Triangle and the Binomial Theorem is shared under a CC BY-NC-ND license and was authored, remixed, and/or curated by RichardHammack.

Page 49: MATH E MATI CS ADV ANCE D MAT 3 1 0 BR I DGE TO

Richard Hammack 4.6.1 5/4/2022 https://math.libretexts.org/@go/page/33712

4.6: Section 6-ExercisesUse the method of direct proof to prove the following statements.

Exercise If x is an even integer, then is even.

Exercise If x is an odd integer, then is odd.

Exercise If a is an odd integer, then is odd.

Exercise

Suppose . If x and y are odd, then xy is odd.

Exercise Suppose . If x is even, then xy is even.

Exercise Suppose . If and , then .

Exercise Suppose . If , then .

Exercise

Suppose a is an integer. If , then .

Exercise

Suppose a is an integer. If , then .

Exercise Suppose a and b are integers. If , then .

Exercise Suppose . If and , then .

Exercise

If and , then .

Exercise Suppose . If , then or .

Exercise If , then is odd. (Trycases.)

Exercise

If , then is even. (Trycases.)

4.6.1

x2

4.6.2

x3

4.6.3

+3a+5a2

4.6.4

x, y ∈ Z

4.6.5

x, y ∈ Z

4.6.6

a, b, c ∈ Z a|b a|c a|(b+c)

4.6.7

a, b ∈ Z a|b |a2 b2

4.6.8

5|2a 5|a

4.6.9

7|4a 7|a

4.6.10

a|b a|(3 −b2 +5b)b3

4.6.11

a, b, c, d ∈ Z a|b c|d ac|bd

4.6.12

x ∈ R 0 < x < 4 ≥ 14x(4−x)

4.6.13

x, y ∈ R +5y = +5xx2 y2 x = y x+y = 5

4.6.14

n ∈ Z 5 +3n+7n2

4.6.15

n ∈ Z +3n+4n2

Page 50: MATH E MATI CS ADV ANCE D MAT 3 1 0 BR I DGE TO

Richard Hammack 4.6.2 5/4/2022 https://math.libretexts.org/@go/page/33712

Exercise If two integers have the same parity, then their sum is even. (Try cases.)

Exercise If two integers have opposite parity, then their product is even.

Exercise Suppose x and y are positive real numbers. If , then .

Exercise

Suppose a, b and c are integers. If and , then .

Exercise

If a is an integer and , then .

Exercise If p is prime and k is an integer for which , then p divides .

Exercise

If , then . (You may need a separate case for .)

Exercise

If , then is even.

Exercise If and , then the numbers are all composite. (Thus for any , onecan find consecutive composite numbers. This means there are arbitrarily large “gaps” between prime numbers.)

Exercise

If and , then .

Exercise

Every odd integer is a difference of two squares. (Example , etc.)

Exercise Suppose . If , then or b is not prime.

Exercise

Let . Suppose a and b are not both zero, and . Prove that .

4.6: Section 6-Exercises is shared under a CC BY-NC-ND license and was authored, remixed, and/or curated by Richard Hammack.

4.6.16

4.6.17

4.6.18

x < y <x2 y2

4.6.19

|ba2 |cb3 |ca6

4.6.20

|aa2 a ∈ {−1, 0, 1}

4.6.21

0 < k < p ( )pk

4.6.22

n ∈ N = 2( )+( )n2 n2

n1 n = 1

4.6.23

n ∈ N ( )2nn

4.6.24

n ∈ N n ≥ 2 n! +2,n! +3,n! +4,n! +5, ⋯ ,n! +n n ≥ 2

n−1

4.6.25

a, b, c ∈ N c ≤ b ≤ a ( )( ) = ( )( )a

b

a

c

a

b−c

a−b+c

c

4.6.26

7 = −42 32

4.6.27

a, b ∈ N gcd(a, b) > 1 b|a

4.6.28

a, b, c ∈ Z c ≠ 0 c ⋅ gcd(a, b) ≤ gcd(ca, cb)

Page 55: MATH E MATI CS ADV ANCE D MAT 3 1 0 BR I DGE TO

Richard Hammack 5.4.1 5/4/2022 https://math.libretexts.org/@go/page/33717

5.4: Section 4-A. Prove the following statements with contrapositive proof. (In each case, think about how a direct proof would work. In mostcases contrapositive is easier.)

Exercise Suppose . If is even, then n is even.

Exercise Suppose . If is odd, then n is odd.

Exercise Suppose . If is odd, then a and b are odd.

Exercise

Suppose . If a does not divide bc, then a does not divide b.

Exercise Suppose . If then .

Exercise Suppose . If then .

Exercise Suppose . If both ab and are even, then both a and b are even.

Exercise

Suppose . If , then .

Exercise

Suppose . If , then .

Exercise Suppose and . If , then and .

Exercise Suppose . If is even, then x is even or y is odd.

Exercise Suppose . If is not divisible by 4, then a is odd.

Exercise

Suppose . If , then .

B. Prove the following statements using either direct or contrapositive proof.

Exercise If and a and b have the same parity, then and do not.

5.4.1

n ∈ Z n2

5.4.2

n ∈ Z n2

5.4.3

a, b ∈ Z ( −2b)a2 b2

5.4.4

a, b, c ∈ Z

5.4.5

x ∈ R +5x < 0x2 x < 0

5.4.6

x ∈ R −x > 0x3 x > −1

5.4.7

a, b ∈ Z a +b

5.4.8

x ∈ R −4 +3 − +3x −4 ≥ 0x5 x4 x3 x2 x ≥ 0

5.4.9

n ∈ Z 3�� ∤ n2 3�� ∤ n

5.4.10

x, y, z ∈ Z x ≠ 0 x ∤ ��yz x ∤ ��y x ∤ ��z

5.4.11

x, y ∈ Z (y +3)x2

5.4.12

a ∈ Z a2

5.4.13

x ∈ R +7 +5x ≥ + +8x5 x3 x4 x2 x ≥ 0

5.4.14

a, b ∈ Z 3a +7 7b −4

Page 56: MATH E MATI CS ADV ANCE D MAT 3 1 0 BR I DGE TO

Richard Hammack 5.4.2 5/4/2022 https://math.libretexts.org/@go/page/33717

Exercise Suppose . If is even, then x is odd.

Exercise Suppose . If is even, then x and y have the same parity.

Exercise If n is odd, then .

Exercise

If , then .

Exercise

Let and . If and , then .

Exercise If and , then .

Exercise Let and . If , then .

14. Let a∈Z, n∈N. If a has remainder r when divided by n, then a≡r (mod n).

15. Leta,b∈Zandn∈N.Ifa≡b(modn),thena2≡ab(modn).

16. If a≡b (mod n) and c≡d (mod n), then ac≡bd (mod n).

17. Letn∈N.If2n−1isprime,thennisprime.

18. Ifn=2k−1fork∈N,theneveryentryinRownofPascal’sTriangleisodd.

19. If a≡0 (mod 4) or a≡1 (mod 4), then ��a2�� is even.

20. Ifn∈Z,then4��(n2−3).

21. Ifintegersaandbarenotbothzero,thengcd(a,b)=gcd(a−b,b).

22. Ifa≡b(modn),thengcd(a,n)=gcd(b,n).

23. Suppose the division algorithm applied to a and b yields a = qb + r. Prove gcd(a, b) = gcd(r, b).

24. If a ≡ b (mod n), then a and b have the same remainder when divided by n

5.4.15

x ∈ Z −1x3

5.4.16

x, y ∈ Z x +y

5.4.17

8|( −1)n2

5.4.18

a, b ∈ Z (a +b ≡ + (mod 3))3 a3 b3

5.4.19

a, b, c ∈ Z n ∈ N a ≡ b (mod n) a ≡ c (mod n) c ≡ b (mod n)

5.4.20

a ∈ Z a ≡ 1 (mod 5) ≡ 1 (mod 5)a2

5.4.21

a, b ∈ Z n ∈ N a ≡ b (mod n) ≡ (mod n)a3 b3

Page 60: MATH E MATI CS ADV ANCE D MAT 3 1 0 BR I DGE TO

1 5/4/2022

CHAPTER OVERVIEW

6: Proof by Contradiction6.0: Section 1-6.1: Section 2-6.2: Section 3-6.3: Section 4-6.4: Section 5-6.5: Section 6-

6: Proof by Contradiction is shared under a CC BY-NC-ND license and was authored, remixed, and/or curated by Richard Hammack.

Page 67: MATH E MATI CS ADV ANCE D MAT 3 1 0 BR I DGE TO

1 5/4/2022

CHAPTER OVERVIEW

7: Proving Non-Conditional Statements7.0: Section 1-7.1: Section 2-7.2: Section 3-7.3: Section 4-7.4: Section 5-7.5: Section 6-

7: Proving Non-Conditional Statements is shared under a CC BY-NC-ND license and was authored, remixed, and/or curated by RichardHammack.

Page 86: MATH E MATI CS ADV ANCE D MAT 3 1 0 BR I DGE TO

1 5/4/2022

CHAPTER OVERVIEW

10: Mathematical Induction10.0: Section 1-10.1: Section 2-10.2: Section 3-10.3: Section 4-10.4: Section 5-10.5: Section 6-

10: Mathematical Induction is shared under a CC BY-NC-ND license and was authored, remixed, and/or curated by Richard Hammack.

Page 121: MATH E MATI CS ADV ANCE D MAT 3 1 0 BR I DGE TO

1 5/4/2022 https://math.libretexts.org/@go/page/37970

IndexAaddition principle

3.2: The Addition and Subtraction Principles

BBiconditional Statement

2.3: Biconditional Statements binomial theorem

3.5: Pascal’s Triangle and the Binomial Theorem

Ddifference

1.5: Union, Intersection, Difference

Eelements

1.1: Introduction to Sets

Ffactorial

3.3: Factorials and Permutations

Iindexed sets

1.8: Indexed Sets intersection

1.5: Union, Intersection, Difference

Oordered pairs

1.2: The Cartesian Product

PPascal's Triangle

3.5: Pascal’s Triangle and the Binomial Theorem permutations

3.3: Factorials and Permutations Power Sets

1.4: Power Sets

Proof by Contradiction6: Proof by Contradiction

Sset

1.1: Introduction to Sets subtraction principle

3.2: The Addition and Subtraction Principles

TTruth Table

2.4: Truth Tables for Statements

Uunion

1.5: Union, Intersection, Difference

VVenn diagrams

1.7: Venn Diagrams