University of Arizona

Math 407, Fall 2008, Functions Module

Goals

In the functions module we continue our focus on the structure and meaning of algebraic expressions, but apply them to the concept of function. Functions are to algebra what variables are to arithmetic. Just as in algebra, variables are used to represent numbers, in the study of functions we use letters to represent entire functional relationships. Our goal in this section is to sort out the relationship between these levels of abstraction, and develop ways of thinking about functions that would help high school students see the difference between them.

Syllabus

Sep 17, 19: Extended analysis

Extended analysis of a high school mathematics problem (see sidebar).


Sep 24, 26: The role of definitions

Definition of logarithm, deriving the properties of logarithms from the properties of exponents.


Oct 1, 3: The role of proof

Comparison of growth rates of power functions and exponential functions. Development of a proof that exponentials grow faster than powers.


Car A sets out going at 50 mph. Starting 3 hours later, car B tries to catch up. If car B goes at 75 mph, when does B catch up with A?

  • Solve the problem with the constants replaced by parameters: Car A going at vA mph, car B starting th hours later and going at vB mph.
  • Think of the solution as a function of the parameters. How does it depend on the head-start time, th?
  • How does it depend on the velocities? Can you rewrite the expression for the function to bring out these dependencies more clearly?
From Rethinking Secondary Mathematics, part of the TEXTEAMS materials of The Charles A. Dana Center, The University of Texas at Austin.