1. Points, Lines, and Their Graphs
Chapter 8
Section 8.2

2. Objective
Students will graph ordered pairs and linear equations in two variables

3. Vocabulary
Coordinate plane x-axis y-axis Origin Ordered pair x-coordinate y-coordinate Quadrants (I – IV)

4. Horizontal axis (x)
Vertical axis (y)
Origin
Quadrant I
Quadrant II
Quadrant III
Quadrant IV
Ordered Pair

5. Graph (3, 2) x-coordinate? y-coordinate
Example
Graph (3, 2) x-coordinate? y-coordinate

6. Example
Plot each point in a coordinate plane A(-2, 4) B(4, -2) C(-3, -2) D(0, 4)

7. Concept
The graph of an equation in two variables consists of all the points that are the graphs of the solutions of the equation (all the points that fall on that line). x + 2y = 6 has the ordered pairs (0, 3) (2, 2) (4, 1) (6, 0) & (-2, 4)

8. Concept
All linear equations in the variables x & y can be written in the form ax + by = c where a, b, and c are real numbers with a and b not both zero. If a, b, and c are integers, the equation is said to be in standard form.

9. Concept
Since two points determine a line, you need to find only two solutions of a linear equation in order to graph it. The easiest solutions to find are those where the line crosses the x-axis (y = 0) and the y-axis (x = 0).

10. Example
Graph 2x – 3y = 6

11. Example
Graph x + y = 0

12. Example
Graph x = -2 & y = 3

13. Questions

14. Assignment
Worksheet