1. Drill #61 Find the slope of the line that passes through each pair of points: 1.( 6, -4 ), ( 8, -7 ) 2.( 8, 5 ), ( 8, -1) Determine the value of r so that the line that passes through each pair of points has the given slope: 3. (3, r), (1, 2), m = 2 4. (1, r), (9, 7), m = ¾

2. Drill #62 4-2 Skills Practice #1 – 6

3. 4-2 Slope and Direct Variation Objective: To write and graph direct variation equations, and to solve problems involving direct variation. Open books to page 196.

4. (1.) Direct Variation and (2.) Constant of Varitation** (1.) Direct Variation: A relationship that can be described by the equation y = kx where k = 0. Direct variation equations are proportional. (2.) Constant of Variation: The constant k in a direct variation equation.

5. Slope and Constant Variation* Ex1: Classwork: 4-2 Study Guide #1 – 3

6. Graph a Direct Variation* To graph a direct variation equation Plot a point at the origin From the origin use the slope (rise over run) to plot a second point. Connect the dots (and draw arrows) Ex2a, b. 2A, B, C, D: Check your progress.

7. (3.) Family of graphs and (4.) parent graph (3.) Family of graphs: A set of graphs and equations that have at least one characteristic in common. (4.) Parent graph: The simplest graph in a family of graphs. Ex2:

8. Write and Solve Direct Variation Equations* To write and solve direct variation equations you need to find the constant of variation k. Ex3a, b. Classwork: 4-2 Skills Practice #7-12

9. Real World Example* Ex4: Biology, pg 199 4A, B, C.