1. Learning Target
Students will be able to: Identify, write, and graph direct variation.

2. A recipe for paella calls for 1 cup of rice to make 5 servings
A recipe for paella calls for 1 cup of rice to make 5 servings. In other words, a chef needs 1 cup of rice for every 5 servings.

3. A direct variation is a special type of linear relationship that can be written in the form y = kx, where k is a nonzero constant called the constant of variation.

4. Tell whether each equation represents a direct variation
Tell whether each equation represents a direct variation. If so, identify the constant of variation.
y = 3x
3x + y = 8
–4x + 3y = 0

5. What happens if you solve y = kx for k?
So, in a direct variation, the ratio is equal to the constant of variation.

6. Tell whether the relationship is a direct variation. Explain.

7. Tell whether each relationship is a direct variation. If it is, explain.

8. The value of y varies directly with x, and y = 3, when x = 9
The value of y varies directly with x, and y = 3, when x = 9. Find y when x = 21.

9. A group of people are tubing down a river at an average speed of 2 mi/h. Write a direct variation equation that gives the number of miles y that the people will float in x hours. Then graph.
distance (mi)

10. The perimeter y of a square varies directly with its side length x
The perimeter y of a square varies directly with its side length x. Write a direct variation equation for this relationship. Then graph.
Perimeter
HW pp. TBD 

11. Learning Targets Write a linear equation in slope-intercept form.
Graph a line using slope-intercept form.

12. Graph the line given the slope and y-intercept.

13. Graph the line given the slope and y-intercept.
slope = 4; y-intercept =

14. Graph the line given the slope and y-intercept.
slope = 2, y-intercept = –3

15. Graph the line given the slope and y-intercept.
slope = , y-intercept = 1

16. Write the equation that describes the line in slope-intercept form.
slope = ; y-intercept = 4

17. Write the equation that describes the line in slope-intercept form.
slope = –9; y-intercept =

18. Write the equation that describes the line in slope-intercept form.
slope = 2; (3, 4) is on the line

19. Graph the line described by the equation.
y = 3x – 1

20. Graph the line described by the equation.
2y + 3x = 6

21. HW pp. 329/10-34 even & pp /13-29,31 
Graph the line described by the equation.
y = –4