C O M A P ’ S Pre-Calculus TEACHER’S RESOURCES DEVELOPED BY COMAP, Inc. 175 Middlesex Turnpike, Suite 3B Bedford, Massachusetts 01730 PROJECT LEADERSHIP Solomon Garfunkel COMAP, INC., BEDFORD, MA Landy Godbold THE WESTMINSTER SCHOOLS, ATLANTA, GA Henry Pollak TEACHERS COLLEGE, COLUMBIA UNIVERSITY, NY, NY Mathematics: Modeling Our World
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C O M A P ’ S
Pre-CalculusT E A C H E R ’ S R E S O U R C E S
DEVELOPED BY
COMAP, Inc.175 Middlesex Turnpike, Suite 3B
Bedford, Massachusetts
01730
PROJECT LEADERSHIP
Solomon GarfunkelCOMAP, INC., BEDFORD, MA
Landy GodboldTHE WESTMINSTER SCHOOLS, ATLANTA, GA
Henry PollakTEACHERS COLLEGE, COLUMBIA UNIVERSITY, NY, NY
The Consortium for Mathematics and Its Applications (COMAP)
175 Middlesex Turnpike, Suite 3B
Bedford, Massachusetts
01730
Published and distributed by
The Consortium for Mathematics and Its Applications (COMAP)175 Middlesex Turnpike, Suite 3B
Bedford, Massachusetts 01730
All rights reserved. The text of this publication, or any part thereof, may not be reproduced
or transmitted in any form or by any means, electronic or
mechanical, including photocopying, recording, storage in an information retrieval system, or otherwise,
without prior written permission of the publisher.
This book was prepared with the support of NSF Grant ESI-9255252. However, any opinions,
findings, conclusions, and/or recommendations herein are those of the authors
and do not necessarily reflect the views of the NSF.
ISBN 0-7167-4114-8
Printed in the United States of America.
EDITOR: Landy Godbold
AUTHORS: Nancy Crisler, PATTONVILLE SCHOOL DISTRICT, ST. ANN, MO; Marsha Davis, EASTERN CONNECTICUT STATE UNIVERSITY, WILLIMANTIC, CT
Gary Froelich, COMAP, INC., LEXINGTON, MA; Frank Giordano, U. S. MILITARY ACADEMY (RETIRED);
Jerry Lege, DR. JAMES HOGAN SENIOR HIGH SCHOOL, VALLEJO, CA
iiiMathematics: Modeling Our World
To the Teacher
Since its inception in 1980, COMAP has been dedicated to presenting mathematics
through contemporary applications. We have produced high school and college texts,
hundreds of supplemental modules, and three television courses—all with the purpose
of showing students how mathematics is used in their daily lives.
After the publication of the NCTM Standards in 1989, the National Science Foundation began to fund
major curriculum projects at the elementary, middle, and secondary levels. The purpose of all of these
programs is to turn the vision of the Standards into the curriculum of today’s classrooms. In 1992, the
ARISE project was one of only five such high school programs selected by the NSF for funding.
Over the past eight years, we have worked to develop this curriculum with a team of over 20 authors,
almost all practicing high school teachers, including several Presidential Awardees and Woodrow Wilson
Fellows. We have field-tested these materials with over 10,000 students across the country. Both our author
team and our field-testers come from an amazingly diverse collection of schools with a full range of
student populations.
The result of these labors is Mathematics: Modeling Our World. In the COMAP spirit, Mathematics: Modeling
Our World develops mathematical concepts in the contexts in which they are actually used. The word
“modeling” is the key. Real problems do not come at the end of chapters. Real problems don’t look like
mathematics problems. Real problems are messy. Real problems ask questions such as: How do we create
computer animation? How do we effectively control an animal population? What is the best location for a
fire station? What do we mean by “best”?
Mathematical modeling is the process of looking at a situation, formulating a problem, finding a
mathematical core, working within that core, and coming back to see what mathematics tells us about the
original problem. We do not know in advance what mathematics to apply. The mathematics we settle on
may be a mix of geometry, algebra, trigonometry, data analysis, and probability. We may need to use
computers or graphing calculators, spreadsheets, or other utilities.
At heart, we want to demonstrate to students that mathematics is the most useful subject they will learn.
More importantly, we hope to demonstrate that using mathematics to solve interesting problems about
how our world works can be a truly enjoyable and rewarding experience. Ultimately, learning to model is
learning to learn.
For those of you who have taught the earlier courses in this series, you will note one major difference. In
Mathematics: Modeling Our World Courses 1, 2, and 3 all of the chapters were organized around a major
context. We did this to emphasize further the broad applicability of the subject. In this text we have used
mathematical concepts as chapter titles. We have done this to emphasize that mathematics as a discipline
has a structure of its own, and that as students go on into the study of mathematics they will learn more
and more of that structure and the power it provides to solve an amazingly wide array of problems.
This course is the gateway to collegiate mathematics. As such, students will see a number of essential new
concepts and be asked to learn a number of important new skills.
While we have subtitled the course, pre-calculus, we believe that the material in this text can provide
students with a firm background for any entry-level undergraduate mathematics course—continuous or
discrete. For example, we have provided substantial material on matrices and vectors as well as a full
chapter on discrete dynamical systems. We believe that the treatment of these topics will prepare students
for a deeper understanding of the concepts underlying the calculus as well as those underlying discrete
mathematical structures.
What you will find here is a challenging pre-calculus course for serious students. And, in the COMAP
tradition, you will find exciting, contemporary, applications and models presented in novel ways to help
teach and motivate the further study of our discipline.
Solomon Garfunkel
CO-PRINCIPAL INVESTIGATOR
Landy Godbold
CO-PRINCIPAL INVESTIGATOR
Henry PollakCO-PRINCIPAL INVESTIGATOR
iv ACKNOWLEDGEMENTS Mathematics: Modeling Our World
AcknowledgementsPROJECT LEADERSHIP
Solomon Garfunkel COMAP, INC., LEXINGTON, MA
Landy Godbold, THE WESTMINSTER SCHOOLS, ATLANTA, GAHenry PollakTEACHERS COLLEGE, COLUMBIA UNIVERSITY, NY
EDITOR
Landy Godbold
AUTHORS
Nancy CrislerPATTONVILLE SCHOOL DISTRICT, ST. ANN, MO
Gary FroelichSECONDARY SCHOOL PROJECTS MANAGER, COMAP, INC., LEXINGTON, MA
Frank GiordanoU. S. MILITARY ACADEMY (RETIRED)
Jerry LegeDR. JAMES HOGAN SENIOR HIGH SCHOOL, VALLEJO, CA
REVIEWERS
Marsha Davis EASTERN CONNECTICUT STATE UNIVERSITY, WILLIMANTIC, CT
Dédé de Haan, Jan de Lange, Henk van der KooijFREUDENTHAL INSTITUTE, THE NETHERLANDS
Henry PollakTEACHERS COLLEGE, COLUMBIA UNIVERSITY, NY
ASSESSMENT
Dédé de Haan, Jan de Lange, Anton Roodhardt, Henk van der KooijTHE FREUDENTHAL INSTITUTE, THE NETHERLANDS
EVALUATION
Barbara FlaggMULTIMEDIA RESEARCH, BELLPORT, NY
FIELD TEST SCHOOLS AND TEACHERS
Gresham Union High School, Gresham, ORKAY FRANCIS
Mills E. Godwin High School, Richmond, VAANN W. SEBRELL
Riverdale High School, Marylhurst, ORDAVID THOMPSON
Sam Barlow High School, Gresham, ORBRAD GARRETT
COMAP STAFF
Solomon Garfunkel, Laurie Aragón, Sheila Sconiers, Sue Rasala,Gary Froelich, Roland Cheyney, Sue Martin, Lynn Aro, Sue Judge,George Ward, Daiva Kiliulis, Gail Wessell, Pauline Wright, Gary Feldman, Clarice Callahan, Jan Beebe, Rafael Aragón, Kevin Darcy, Peter Bousquet
Recreation, Information Science,Management, Cryptography, History
CHAPTER 8
History, Personal Finance, Physical Science,Law Enforcement, Medicine, Management,Wildlife Biology
MMOW 4 Related Disciplines
x Mathematics: Modeling Our World
Chapter Objectives
CHAPTER 1
FUNCTIONS IN MODELING
Introduction:
Modeling Behavior: Explanations and Patterns
To reiterate the importance of mathematicalmodeling.
To explain the two types of mathematicalmodels, “theory driven” and “data driven.”
To review the modeling process.
To introduce the course’s first modelingsituation.
Lesson 1.1:
A Theory-Driven Model
To create a theory-driven model when given aspecific situation.
To test a model against actual data.
Lesson 1.2:
Building a Tool Kit of Functions
To create a tool kit of functions by identifyingkey features of five previously studiedfunctions: constant, direct variation, linear,absolute value, and sine.
To examine the equations, shapes of graphs,patterns in tables of values, and verbaldescriptions of these functions.
To review these functions both in purelymathematical exercises and in contextualsettings.
Lesson 1.3:
Expanding the Tool Kit of Functions
To expand the tool kit of functions that wasintroduced in Lesson 1.2.
To explore power functions, the Ladder ofPowers, and the effect of multiplying a powerfunction by a constant.
Lesson 1.4:
Transformations of Functions
To examine the effects of transformations onthe graphs of the tool kit functions.
Lesson 1.5:
Operations on Functions
To explore addition, subtraction,multiplication, and division of functions.
To refine models by adding or multiplyingtwo functions.
CHAPTER 2
THE EXPONENTIAL AND LOGARITHMIC FUNCTIONS
Lesson 2.1:
Exponential Functions
To expand the tool kit of functions byreviewing exponential functions.
To review the order of operations, thestandard form for exponential functions, the characteristic properties of theirgraphs, and patterns in exponential data.
To introduce base e.
Lesson 2.2:
Logarithmic Scale
To introduce students to the problem ofworking with data that span several orders ofmagnitude.
To use earthquake measurements to illustratea need for relative comparisons.
To introduce the log10 scale and investigate itsproperties.
Lesson 2.3:
Changing Bases
To expand the concept of a logarithmic scaleto consider other bases, including the naturalbase e.
To formalize properties of logarithms anddevelop a procedure for changing bases.
xiMathematics: Modeling Our World
To expand methods for evaluatingexpressions and solving equations to usinglogarithms.
Lesson 2.4:
Logarithmic Functions
To expand the tool kit of functions to includelogarithmic functions.
To identify various properties, including theeffect of base on the graph and therelationship between logarithmic andexponential functions of the same base.
Lesson 2.5:
Modeling With Exponential and Logarithm Functions
To extend data analysis tools by usinglogarithms to develop log-log and semi-logtests through re-expression of original data.
Lesson 2.6:
Composition and Inverses of Functions
To introduce composition as an operation ontwo functions, and to formalize therelationship between a function and itsinverse with respect to composition.
To explore conditions for the existence of aninverse and methods for finding a function’sinverse.
CHAPTER 3
POLYNOMIAL MODELS
LESSON 3.1:
Modeling Falling Objects
To introduce polynomials.
To create and evaluate polynomial models forreal-world phenomena.
Lesson 3.2:
The Merits of Polynomial Models
To create and evaluate polynomial models forreal-world phenomena.
To find a polynomial function that capturesevery point in a set of data.
Lesson 3.3:
The Power of Polynomials
To create and evaluate polynomial models forreal-world phenomena.
To examine the relationship between thedegree of a polynomial function and theshape of its graph.
To find approximations of a polynomialfunction’s x-intercepts and exact x-interceptsin some cases.
To examine the relationship between themultiplicity of a zero and the shape of thegraph near that zero.
Lesson 3.4:
Zeroing in on Polynomials
To introduce complex numbers and theFundamental Theorem of Algebra in ahistorical context.
To find complex zeros of some polynomials.
To perform basic operations on complexnumbers.
Lesson 3.5:
Polynomial Divisions
To examine asymptotic behavior in rationalfunctions.
Lesson 3.6:
Polynomial Approximations
To introduce power series approximations ofexponential and trigonometric functions.
To explain the difference between convergentand divergent series.
CHAPTER 4
COORDINATE SYSTEMS AND VECTORS
Lesson 4.1:
Polar Coordinates
To introduce polar coordinates and methodsfor expressing directional angles.
To develop and apply formulas for convertingbetween rectangular and polar coordinates.
xii Mathematics: Modeling Our World
Lesson 4.2:
Polar Form of Complex Numbers
To represent complex numbers usingpolar coordinates.
To evaluate powers and roots of complexnumbers by use of De Moivre’s Theorem.
Lesson 4.3:
The Geometry of Vectors
To examine vectors from a geometricperspective.
To define magnitude, direction angle,vector addition and subtraction, andmultiplication by scalars.
To introduce basis vectors and resolutionof vectors into components.
Lesson 4.4:
The Algebra of Vectors
To re-examine the concepts, properties,and operations of vectors from analgebraic perspective.
To express vectors as linear combinationsof basis vectors.
To introduce the scalar (dot) product ofvectors
To introduce the Laws of Sines andCosines.
Lesson 4.5:
Vector Equations in Two Dimensions
To model motion (linear and nonlinear)using vector equations.
To relate vector equations for lines toparametric and two-variable forms ofequations for lines.
Lesson 4.6:
Vector Equations in Three Dimensions
To extend the Cartesian coordinate systemto three dimensions.
To generalize vectors to three-dimensionalspace.
To extend vector equation concepts,properties, and operations to model three-dimensional motion.
To introduce vector (cross) products.
CHAPTER 5
MATRICES
Lesson 5.1:
Matrix Basics
To review basic matrix concepts.
To provide practice with matrixoperations, including the use ofcalculators/computers to perform theseoperations.
Lesson 5.2:
The Multiplicative Inverse
To solve matrix equations.
To solve a system of equations by writingand solving a related matrix equation.
Lesson 5.3:
Systems of Equations in Three Variables
To represent systems of three equations inthree unknowns geometrically.
To determine whether a system of threeequations in three unknowns has nosolutions, one solution, or many solutions,and to describe existing solutions.
To solve systems of three equations inthree unknowns by writing and solving arelated matrix equation or by reducing anaugmented matrix.
CHAPTER 6
ANALYTIC GEOMETRY
Lesson 6.1:
Analytic Geometry and Loci
To investigate the usefulness of analytic(coordinate) geometry in solving problemsthat can be modeled geometrically.
xiiiMathematics: Modeling Our World
To introduce the concept of locus.
To introduce the idea of coordinate proof.
To apply coordinate geometry in threedimensions.
To review the distance formula, themidpoint formula, the slopes of parallellines, the slopes of perpendicular lines, thepoint-slope form of the equation of a line,and the definitions of some geometricfigures.
Lesson 6.2:
Modeling with Circles
To construct a circle and discover anequation for it using its locus definition.
To find the center and radius of a circlewhen given its equation.
To graph a circle when given its equation.
To find the equation of a circle when givencertain information.
To apply the knowledge of circles tospheres.
To investigate and apply the properties ofcircles to real-world situations.
Lesson 6.3:
Modeling with Parabolas
To use the locus definition for a parabolato construct and develop an equation forit.
To find the vertex, focus and directrix of a parabola when the equation is given.
To graph a parabola given its equation.
To find the equation of a parabola whengiven certain information.
To recognize and apply the reflectionproperty of the parabola.
To investigate and apply the properties of parabolas to real-world situations.
Lesson 6.4:
Modeling with Ellipses
To construct an ellipse and develop anequation for it using its locus definition.
To find the center, foci, and endpoints ofthe major and minor axes when given theequation of an ellipse.
To graph an ellipse when given itsequation.
To find the equation of an ellipse whengiven certain information.
To recognize and apply the reflectionproperty of the ellipse.
To investigate and apply the properties ofellipses to real-world situations.
Lesson 6.5:
Modeling with Hyperbolas
To construct a hyperbola and develop anequation for it using its locus definition.
To find the center, foci, vertices andasymptotes of a hyperbola when given itsequation.
To graph a hyperbola when given itsequation.
To find the equation of a hyperbola whengiven certain information.
To recognize and apply the reflectionproperty of the hyperbola.
To investigate and apply the properties ofhyperbolas to real-world situations.
To identify, compare, and contrast the fourconics.
xiv Mathematics: Modeling Our World
CHAPTER 7
COUNTING AND THE BINOMIAL THEOREM
Lesson 7.1:
Counting Basics
To solve counting problems by severalmethods: making a list, the basicmultiplication principle, permutations,and combinations.
To apply counting methods to probabilityproblems.
Lesson 7.2:
Compound Events
To use addition and multiplicationprinciples to determine the number ofways that compound events can occur.
To modify and apply the additionprinciple to counting problems in whichevents overlap.
Lesson 7.3:
The Binomial Theorem
To use the binomial theorem to raisealgebraic binomials to powers.
To establish connections amongcombinations, binomial coefficients, andPascal’s triangle.
CHAPTER 8
MODELING CHANGE WITHDISCRETE DYNAMICAL SYSTEMS
Lesson 8.1:
Modeling Change with Difference Equations
To define difference equations.
To use difference equations to build andsolve models that exactly model abehavior.
Lesson 8.2:
Approximating Change with Difference Equations
To define the first difference of a sequence.
To use the concept of proportionality tobuild difference equations that approximatea behavior.
Lesson 8.3:
Numerical Solutions
To find equilibrium values and investigatetheir stability numerically.
To determine long-term behavior byexamining and classifying equilibria interms of the forms of the definingdifference equations.
Lesson 8.4:
Systems of Difference Equations
To model economic, ecological, andpolitical systems with more than onedependent variable.
To investigate numerically the long-termbehaviors of the systems modeled.