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Five-Minute Check (over Lesson 8–5) Then/Now New Vocabulary Example 1: Real-World Example: Use Rise and Run to Find Slope Example 2: Use a Graph to Find Slope Key Concept: Slope Example 3: Use Coordinates of Points to Find Slope Example 4: Zero and Undefined Slopes Lesson Menu

Find the constant rate of change for the linear function. A. $1 per bag B. $2 per bag C. $3 per bag D. $5 per bag 5-Minute Check 1

Write a direct variation equation relating x and y if y = 6 when x = 8. B. 6y = 8x C. D. y = 48x 5-Minute Check 2

Write a direct variation equation relating x and y if y = –20 when x = 5. A. y = –80x B. –20y = 5x C. y = –4x D. y = 4x 5-Minute Check 3

The cost of fencing varies directly with the number of feet of fencing purchased. If 1 foot of fencing costs $1.75, find the cost of 200 feet. A. $200.75 B. $275.00 C. $305.00 D. $350.00 5-Minute Check 4

D. No; the ratios are different. Determine if there is a proportional linear relationship between the time and distance traveled. A. yes; constant ratio = 50 B. yes; constant ratio = 42.5 C. yes; constant ratio = 46.4 D. No; the ratios are different. 5-Minute Check 5

Use slope to describe a constant rate of change. You have already used graphs to find a constant rate of change and interpret its meaning. (Lesson 8–5) Find the slope of a line. Use slope to describe a constant rate of change. Then/Now

Slope=Vertical Change/ Rise Horizontal Change/Run Vocabulary

Concept

Write the formula for slope. Use Rise and Run to Find Slope HILLS Find the slope of a hill that rises 30 feet for every horizontal change of 1500 feet. Write the formula for slope. rise = 30 feet, run = 1500 feet Simplify. Answer: Example 1

Find the slope of a hill that rises 40 feet for every horizontal change of 100 feet. B. C. D. Example 1

A. Find the slope of the line. Use a Graph to Find Slope A. Find the slope of the line. run = 1 rise = 3 Answer: The slope is 3. Example 2 A

B. Find the slope of the line. Use a Graph to Find Slope B. Find the slope of the line. run = 6 rise = –2 Example 2 B

A. Find the slope of the line. B. C. D. Example 2 CYP A

B. Find the slope of the line. A. B. C. D. Example 2 CYP B

Find the slope of the line that passes through B(2, 7) and C(–3, –2). Use Coordinates of Points to Find Slope Find the slope of the line that passes through B(2, 7) and C(–3, –2). Definition of slope (x1, y1) = (2, 7) (x2, y2) = (–3, –2) Answer: Example 3

Find the slope of the line that passes through A(–2, 4) and B(5, –1). C. D. Example 3

Zero and Undefined Slopes A. Find the slope of the line that passes through A(–3, 3) and B(2, 3). Definition of slope (x1, y1) = (–3, 3) (x2, y2) = (2, 3) Simplify. Answer: The slope is 0. Example 4

Division by 0 is undefined. Zero and Undefined Slopes B. Find the slope of the line that passes through P(2, 3) and Q(2, –2). Definition of slope (x1, y1) = (2, 3) (x2, y2) = (2, –2) Division by 0 is undefined. Answer: The slope is undefined. Example 4

A. Which pair of points would be connected by a line with a slope equal to 0? A. (1, 1) and (2, 2) B. (1, 1) and (2, 1) C. (1, 1) and (1, 2) D. (1, 1) and (–1, 2) Example 4 CYP A

B. Which pair of points would be connected by a line with a slope that is undefined? A. (1, 1) and (2, 2) B. (1, 1) and (2, 1) C. (1, 1) and (1, 2) D. (1, 1) and (–1, 2) Example 4 CYP B

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