Topic: Functions and Graphs I
Subtopic: Functions I - Introduction
Overview
Today we introduce the concepts of functions and relations. Relations will be given in the form of sets of ordered pairs, mappings, graphs, or equations. Try to seem these as just different ways to visualize/communicate the same information.
This is a vital section since the remainder of this course and intermediate algebra deal with different types of functions and their graphs. There is lots of important terminology here. Be sure you well versed in recognizing functions given a set of ordered pairs (e.g., why is {(0,1),(0,2),(1,3),(2,3)} not a function?), a mapping, a graph (using the VLT), or an equation (which you can just graph and determine visually).
A key thing to remember is that if a relation has "same x different y" then it is NOT a function.
Notation Caution: f(x) ... that is "f of x" ... does not mean f times x! It does mean the equation is a function called f and the input variable is x. You can think of "f(x)" as meaning "y". In other words, "Evaluate y=x3 or x=2" means the same thing as "Given f(x)=x3 find f(2)".
Objectives
By the end of this topic you should know and be prepared to be tested on:
- 3.3.1 Determine if a relation is a function or not given: set of ordered pairs, mapping, graph, or equation
- 3.3.2 Use the vertical line test to determine if a curve is a graph of a function or not
- 3.3.3 Understand function notation and use/write it properly
- 3.3.4 Evaluate functions algebraically for given values of the input variable
- 3.3.5 Evaluate functions by observation of its graph
Terminology
Define: set, mapping, relation, function, vertical line test (VLT)
Text Notes
Text:
Intro & Inter Algebra for CS 3ed by Blitzer, sect. 8.1
- This section contains lots of important new terminology, notation, and processes. Plan to spend significant time studying it!
- ch 8.1-8.3 Caution: The text covers foil before functions, but the Clark elementary algebra curriculum covers functions first. So we jumped ahead to chapter 8 to pick up functions but the text includes foil in some of the exercises. THERE WILL BE NO FOIL PROBLEMS ON THIS WEEK'S QUIZ! We'll leave those until after we cover foil later in the course. So there will be NO problems such as simplify a function that has a binomial times a binomial like (x+2)(x-1) because to do that multiplication involves foil. You can SKIP any exercises that involve multiplying a binomial times a binomial.