Topic: Functions and Graphs I
Subtopic: Introduction to Graphing
Overview
Mathematics can be represented algebraically (with variables and equations as we have been doing), numerically (with tables of data), or graphically. It is this latter method on which we concentrate today. Concentrate on the graphing related terminology, then plotting points, then graphing lines by making a plug-n-chug chart. By the end of this course you will be expert graphers analyzing mathematical applications by hand as well as by using a graphing calculator or related electronic graphing device. The next few sections of material are visually inspiring which is a pretty cool way to learn algebra!
Objectives
By the end of this topic you should know and be prepared to be tested on:
- 3.1.1 Signs of the x and y-coordinates of points in each of the four quadrants
- 3.1.2 Analyze graphs that represent real-life data by being able to answer questions about a real-life situation by "reading" a given graph of the data
- 3.1.3 Given the graph of a line find a point that lies upon it including its x and y-intercept points
- 3.1.4 Given a set of points or chart of data points, plot the points and connect to form a line
- 3.1.5 Graph a line by the plug-n-chug method (a.k.a. point-plotting method), i.e., given a linear equation, form a chart of points that
- 3.1.6 Recognize that real-life data that grows (or falls) in a constant manner can be modeled by a linear equation
Terminology
Define: axes, quadrants, origin, points, coordinates, axis-intercept points, plug-n-chug (a.k.a. point-plotting)
Text Notes
Text:
Intro & Inter Algebra for CS 3ed by Blitzer, sect. 3.1
- This section begins with important terminology of graphs and graphing. It then covers plotting points and checking if a point is a solution to an equation, i.e. if the point lies on the graph of the equation.
- Starting at the bottom of page 201 the text covers graphing an equation by the plug-n-chug chart method. The charts of data points introduced in example 5 are often called plug-n-chug charts since you are plugging in x-values and chugging out y-values (or visa versa). This text calls the plug-n-chug method of graphing "point-plotting"; either way it means to generate a table of points, plot them, and connect to form the line. This method is useful for graphing any equation not just lines!
- Example 8 is an interesting read but IMO too advanced for this level class. You will not be tested on this level of mathematical modeling.
Supplementary Resources
You will need access to a (free) online grapher, graphing software for your computer, or a handheld graphing calculator for the remainder of this class. These MathOL FAQs contain helpful info:
- Where can I find a free online grapher or graphing software for my computer?
- I want to purchase a handheld graphing calculator. Which one should I buy and where?
- I need a tutorial on how to use my graphing calculator. Where can I turn for help?
- Where online can I find some free printable graph paper?