Topic: Lines and their Graphs
Subtopic: Intercept Points
Overview
Hopefully you are beginning to feel more comfortable with functions, graphs, and your electronic grapher as this chapter is graphing intensive. Over the next few days we are going to learn all about graphing lines and analyzing linear functions. Most of our work will be algebraic, but we will also verify our findings electronically and use the technology to expand basic problems into more complicated and realistic applications. The main topic that we study today is to find x and y-intercept points of a line and graph the line using those points. You should be able to do this algebraically by:
- Find the x-intercept point by letting y=0 and solving for x. The x-intercept point will be of the form (#,0).
- Find the y-intercept point by letting x=0 and solving for y. The y-intercept point will be of the form (0,#).
You should also be able to find the intercept points electronically by:
- Use the ZERO feature of your grapher to find the exact x-intercept point.
- Use the EVALUATE feature of your grapher to find the exact y-intercept point.
Objectives
By the end of this topic you should know and be prepared to be tested on:
- 4.1.1 Find x and y-axis intercept points of a line algebraically
- 4.1.2 Find x and y-axis intercept points of a line electronically
- 4.1.3 Graph lines by the intercept method
- 4.1.4 Graph horizontal and vertical lines algebraically
Terminology
Define: linear equation in two variables, standard form vs. general form (of a linear equation in two variables)
Text Notes
Text:
Intro & Inter Algebra for CS 3ed by Blitzer, sect. 3.2
- It is a good idea to know ch 3.1 well before beginning to study the rest of chapter 3.
- Examples 2-3 find the x and y-intercept points algebraically. Examples 4-5 graph lines by the intercept method.
- To graph a line on your electronic grapher you must first solve the equation for y. The "using technology" box on page 215 shows the steps to solving an equation for y.
- pg 203 example 8 - Notice that you cannot graph the line x=5 on a calculator. You can graph example 7, y=-3 on a calculator, but not example 8. Why is this??? (Discuss in class.)