Points, Lines, and Their Graphs Chapter 8 Section 8.2

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

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

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

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

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

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)

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.

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).

Example Graph 2x – 3y = 6

Example Graph x + y = 0

Example Graph x = -2 & y = 3

Questions

Assignment Worksheet