1. Algebra 5.1 Writing Linear Equations in Slope Intercept Form

2. Write an equation of the line whose slope m is -2 and whose y-intercept b is 5. m = -2 b = 5 y = mx + b y = -2x + 5

3. Rise -2 Run 1 Graph of y = -2x + 5 m = -2 b = 5 y-intercept (0,5)

4. Writing an Equation of a Line from a Graph STEPS By looking at the graph: 1.Identify the y-intercept b 2.Find another point on the “corner” of a grid box (coordinates are whole numbers) 3.Either count rise and run from b to the other point, or use the slope formula to find m. 4.Plug in m and b to the equation y = mx + b.

5. Example (from graph to equation) b = -2 m = Run 3 Rise 1 Run 3 = 1 3 m = -1 –(-2) 3 - 0 = 1 3 (0,-2) (3,-1) Using visual count: Using slope formula: Equation:

6. Write the equation

7. Write the linear equation A plumber charges $66 for the first hour of a service call and $45 for any additional hours. Write a linear model to reflect the plumber’s charges and use the equation to determine the cost of a 3-hour service call. Let C represent the cost of the service and h represent the number of hours. C = 45h + 66 C = 45(2) + 66 C = 90 + 66 C = 156

8. Turn to page 275 Let’s go through Example 4 together

9. Homework pg. 276 #12-36, 38-40