Calculus of One Variable
2003–2021
Revised February 2021
Table of contents
Acknowledgements 1
Introduction 2
1 Real and Complex Numbers 5
1.1 Sets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.2 Number Sets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.3 The real number line – Intervals . . . . . . . . . . . . . . . . . . . . . . . . 9
1.4 Complex numbers - Cartesian form . . . . . . . . . . . . . . . . . . . . . . . 11
1.5 Arithmetic in Cartesian form . . . . . . . . . . . . . . . . . . . . . . . . . . 14
1.6 The set of complex numbers . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2 Polar Forms of Complex Numbers 26
2.1 Standard Polar form . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2.2 Polar exponential form - Euler’s formula . . . . . . . . . . . . . . . . . . . . 33
2.3 Arithmetic in polar form . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
2.4 Roots of complex numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
2.5 Roots of polynomial equations . . . . . . . . . . . . . . . . . . . . . . . . . 42
2.6 Sine and cosine in terms of exponentials . . . . . . . . . . . . . . . . . . . . 45
2.7 Complex exponential function . . . . . . . . . . . . . . . . . . . . . . . . . 46
Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
3 Functions 52
3.1 Functions – definitions and examples . . . . . . . . . . . . . . . . . . . . . . 52
3.2 Combining functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
3.3 Injective and inverse functions . . . . . . . . . . . . . . . . . . . . . . . . . 58
3.4 Inverse trigonometric functions . . . . . . . . . . . . . . . . . . . . . . . . . 62
3.5 Hyperbolic functions and their inverses . . . . . . . . . . . . . . . . . . . . 63
Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
4 Limits and Continuity 70
4.1 Informal definition of limit . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
4.2 One-sided limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
4.3 The basic limit laws . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
4.4 Limits at infinity – Horizontal asymptotes . . . . . . . . . . . . . . . . . . . 76
4.5 Infinite limits – Vertical asymptotes . . . . . . . . . . . . . . . . . . . . . . 78
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4.6 The squeeze law . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
4.7 Continuous and discontinuous functions . . . . . . . . . . . . . . . . . . . . 82
Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
5 Differentiation 90
5.1 The derivative at a point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
5.2 The derivative as a function . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
5.3 Basic rules of differentiation . . . . . . . . . . . . . . . . . . . . . . . . . . 95
5.4 The chain rule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
5.5 Implicit differentiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
5.6 The Mean Value Theorem . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
6 Applications of Differentiation 103
6.1 Optimizing functions of one variable . . . . . . . . . . . . . . . . . . . . . . 103
6.2 Increasing and decreasing functions . . . . . . . . . . . . . . . . . . . . . . 107
6.3 Concavity and points of inflection . . . . . . . . . . . . . . . . . . . . . . . 111
6.4 Curve sketching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
6.5 L’H?pital’s rule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
7 Taylor Polynomials 123
7.1 An approximation for ex . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
7.2 Taylor polynomials about x= 0 . . . . . . . . . . . . . . . . . . . . . . . . . 126
7.3 Taylor polynomials about x= a . . . . . . . . . . . . . . . . . . . . . . . . . 129
7.4 Taylor’s formula – The remainder term . . . . . . . . . . . . . . . . . . . . . 131
7.5 How good is the Taylor polynomial approximation? . . . . . . . . . . . . . . 132
7.6 Proof of the remainder formula . . . . . . . . . . . . . . . . . . . . . . . . . 134
Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
8 Taylor Series 137
8.1 Infinite series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
8.2 Taylor series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
8.3 Euler’s formula . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
8.4 The binomial series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
8.5 A series for the inverse tan function . . . . . . . . . . . . . . . . . . . . . . 148
Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
9 The Riemann Integral 151
9.1 Riemann sums – The area problem . . . . . . . . . . . . . . . . . . . . . . . 151
9.2 The Riemann integral . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
9.3 Calculating Riemann sums . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
9.4 Properties of the Riemann integral . . . . . . . . . . . . . . . . . . . . . . . 159
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Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
10 Fundamental Theorem of Calculus 164
10.1 Integrals as functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
10.2 The Fundamental Theorem of Calculus I . . . . . . . . . . . . . . . . . . . . 166
10.3 The Fundamental Theorem of Calculus II . . . . . . . . . . . . . . . . . . . 167
10.4 Leibniz Integral Rule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
10.5 The natural logarithm and exponential functions . . . . . . . . . . . . . . . . 171
Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
11 Integration Techniques 178
11.1 Basic rules of integration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
11.2 Integration by substitution . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
11.3 Integration by parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
11.4 Partial fractions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
12 Applications of Integration 193
12.1 Further integration techniques . . . . . . . . . . . . . . . . . . . . . . . . . 193
12.2 Length of a curve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
12.3 Area between two curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
12.4 Solids of revolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
A Formal Definition of Limits 208
B Geometric proof that limx→0 sinx/x= 1 212
C Linear approximations and differentials 214
D The Distance Problem 219
E Growth Rates 223
F Table of Standard Integrals 225
G Answers to Selected Exercises 226
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Acknowledgements
The material in these notes has been developed over many years by the following members
of the School of Mathematics and Statistics:
Eduardo Altmann Mary Myerscough
Sandra Britton Nigel O’Brian
Chris Durrant Sharon Stephen
Dave Galloway Fernando Viera
Jenny Henderson Haotian Wu
Andrew Mathas
1
Introduction
Calculus is one of the major achievements of the 17th century. It plays a key role in almost
every instance where mathematics is applied in the sciences, engineering, or in economics.
Without calculus, we would not have cars, computers, televisions or mobile phones; Einstein
would never have penned his theory of relativity; we would not know of the existence of
DNA; we would never have landed on the moon. The list goes on.
Whether you end up continuing in mathematics or majoring in another field it will be im-
portant for you to learn and understand the meaning of calculus. The reason for this is quite
simple. In high school you can progress simply by memorizing formulas; in university there
will be times when you need to develop formulas for yourself, and this is where a proper
understanding of calculus will be a definite asset.
These notes are intended to supplement the lectures ofMATH1021. Your lecturers will almost
certainly use different examples and they will also explain some of the material in the course
slightly differently from these notes. In some places these notes go into more detail than your
lectures; at other times your lecturer will go into more detail.
Reading mathematics is not like reading a novel; we have to think and struggle with every
sentence. We are professional mathematicians and we are not ashamed to say that in our
research there have been times when we have spent more than a day trying to understand a
single line of mathematics! You will be pleased to know that in this course you should not
have to spend this long on a single sentence; however, there will be times when you do have
to think quite hard to understand what is going on. If you do get stuck then go and ask your
lecturer or tutor to explain it to you!
In addition to thinking when you read mathematics you should also work through the calcu-
lations yourself using pen and paper.
At some places in the notes and in the Appendices we have included material which is more
“advanced” than we expect you to know or understand. You are free to either read these
sections or skip over them, as you wish.
Tutorial problems and Exercise sheets
There are plenty of problems with full solutions for you to practice.
a) Worked examples with full solutions have been included in these lecture notes
throughout all chapters.
b) Exercises are available at the end of the chapters in these notes and answers to Selected
Exercises can be found in Appendix G.
2
Introduction 3
c) Exercise sheets containing problems to be solved before the tutorial session are avail-
able on the MATH1021 web page. Full solutions will be available online at the end of
the corresponding week.
A detailed list of mathematical objectives (knowledge, understanding and skills) for a
given chapter is provided in the weekly Exercise Sheets.
d) Board tutorial sheets will be handed out during tutorials with problems to be solved
during the tutorial class. Full solutions will be available online at the end of the corre-
sponding week.
e) Solutions will be provided to assignments 1 and 2.
f) Questions and solutions to selected past exam papers will be made available near the
end of semester.
Why study mathematics
The study of mathematics enhances your ability to think logically and an-
alytically, move from the particular to the general, work quantitatively and
improve problem-solving skills. By reading and working carefully through
the material in these notes you will develop the following additional generic
skills:
Generalise simple and familiar ideas to more complex settings.
Use geometric/visual techniques to help understand new concepts.
Apply simple techniques in unfamiliar situations.
Estimate values by using suitable approximation techniques.
Recognise that bounds on the error are an important part of any good
approximation.
A note about definitions
A mathematical definition is a precise description of some mathematical con-
cept. Historically, many concepts in mathematics have been used extensively
before a precise definition of the concept has been formulated.
While precision in definitions is certainly important, learning a definition off
by heart, without an understanding of the concept, is unlikely to be helpful.
It is important to spend some time thinking about a definition in order to gain
this understanding.
4 MATH 1021 Calculus of One Variable
C H A P T E R 1
Real and Complex Numbers
Mathematics includes not only the study of logic, structure and geometry, but also ideas about
numbers. Real numbers in particular, are fundamental to calculus and many other branches
of mathematics. In this chapter we review the concepts of sets and extend previous work on
numbers, particularly the real numbers, before introducing the set of complex numbers.
1.1 Sets
Set notation is a convenient and precise way to write about collections of numbers. We start
by talking about general sets.
Definition
A "set" is a collection of objects which are called "members" or "elements"
of the set.
Example 1.1a A set can be written as a list, for example, A= {a,b,c,d}, where
A is the name of the set,
a,b,c,d are the elements of the set enclosed in braces and separated by commas.
If the list of elements is large, three dots may be used to mean ’and so on’. For example,
the set of natural numbers may be denoted by N= {0,1,2,3, . . .}.
1.2 Number Sets
Our understanding of numbers, what they are and how they work, develops from simple
counting through fractions and negative numbers to an appreciation of irrational numbers
and real numbers. Mathematically, different types of numbers belong to different sets.
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6 MATH 1021 Calculus of One Variable
The set of "natural numbers" {0,1,2,3,4, . . .}, is denoted by the symbol N. It is closed
under the operations of addition and multiplication. That is, adding two natural numbers
gives another natural number, as does multiplying them together.
The set of "integers" {. . . ,?4,?3,?2,?1,0,1,2,3,4, . . .}, denoted by Z, is the set of
whole numbers, including both positive whole numbers, negative whole numbers and zero.
The set of integers is closed under the operations of addition, subtraction and multiplication.
The set of "rational numbers", denoted by Q, is the set of all numbers of the form n/m
where n and m are integers and m 6= 0. Some examples are 1