1. 2.4 Graphing Linear Equation Sept 12, 2011

2. Y-intercept a point where a graph intersects the y-axis Vocabulary equation written in the form Ax + By = C where A and B are not both zero Slope-Intercept Form equation written in the form y = mx + b where m is the slope and b is the y-intercept. X-Intercept a point where a graph intersects the x-axis Standard Form

3. Graphing Equations in Slope-Intercept Form Step 1: Using b, plot (0, b) on the graph. Step 2: From (0, b), plot the 2 nd point using the slope (rise/run). Step 3: Draw a line through the two points.

4. Graph 2 yx – = – Example 1 1.Plot y-intercept (b) (0, -2) 2.From there rise 1 unit and go left 1 unit. or Go down 1 unit, go right 1 unit. 3. Connect 2 points with a line b (-1) m

5. Graph Example 2 1.Plot y-intercept (0, 3). 2.From there rise 2 units and go right 3 unit. Place a point. or Go down 2 units, go left 3 units. 3. Connect 2 points with a line b m

6. Checkpoint Graph the equation. 1. = 2 1 yx Use Slope-Intercept Form to Graph a Line

7. Checkpoint Graph the equation. 2. 2 y3x + = – Use Slope-Intercept Form to Graph a Line

8. Checkpoint Graph the equation. 3. = 4 -3 y x + 5 Use Slope-Intercept Form to Graph a Line

9. Graphing Equations in Standard Form Step 1: Find the x-intercept by letting y = 0 and solving for x. Plot (x, 0) Step 2: Find the y-intercept by letting x = 0 and solving for y. Plot (0, y). Step 3: Draw a line through the two points.

10. Example 3 Draw Quick Graphs Graph 3x + 2y = 12 x = 4 Solve for x. STEP 1 Find the x -intercept. 3x3x+ = 12 ( 02 ) Let y = 0. The x -intercept is 4, so plot the point (4, 0). y = 6 Solve for y. 2y2y+ = 12 ( 03 ) Let. x = 0 The y -intercept is 6, so plot the point (0, 6). STEP 2 Find the y -intercept. STEP 3 Draw a line through the intercepts.

11. Checkpoint Graph the equation. 1. x+y = 2 Draw Quick Graphs

12. Checkpoint Graph the equation. 2. 5x5x+2y2y = 10 Draw Quick Graphs

13. Homework : 2.4 p.90 #23-28