1. Slope How did we define slope yesterday?
When looking at a graph to determine if the slope is positive, negative, zero, or undefined what direction should we look?
I want to find the “rise over run” of a line what should I find first on the line?
Explain what we mean by “rise” and “run”.
How might we encounter slope in the real world?

2. The slope of a line is a measure of its steepness and is the ratio of rise to run:y
Run
rise
Rise
slope = x
run
If a line rises from left to right, its slope is positive If a line falls from left to right, its slope is negative A horizontal line has a zero slope A vertical line has an undefined slope.

3. You can graph a line if you know its slope and one of its points.

4. Additional Example 2B: Using Slope and a Point to Graph a Line
1 2
Use the slope and the point (–1, –1) to graph the line. y =
rise
run 1 2 4 2
From point (–1, –1) move 1
unit up and 2 units right. Mark the point where you end up, and draw a line through the two points. x ● –4 –2 2 4 –2 –4

5. Use the slope – and the point (2, 0) to graph the line.
Check It Out: Example 2A
2 3
Use the slope – and the point (2, 0) to graph the line. y = or
rise
run -2 3 2 -3 4 ● 2
From point (2, 0) move 2
units down and 3 units
right, or move 2 units up and 3 unit left. Mark the point where you end up, and draw a line through the two points. x –4 –2 2 4 –2 ● –4

6. Additional Example 3: Identifying Rates of Change in Graphs
Tell whether each graph shows a constant or variable rate of change.
A. B.
The graph is nonlinear,
so the rate of change is variable.
The graph is linear, so
the rate of change is
constant.

7. Lesson Quizzes
Standard Lesson Quiz
Lesson Quiz for Student Response Systems

8. Lesson Quiz for Student Response Systems
1. Tell whether the slope is positive or negative. Then identify the slope.
A. positive; 1
B. positive; 2
C. negative; –1
D. negative; –2

9. Lesson Quiz for Student Response Systems
3. Which of the following graphs represents a variable rate of change?
A B.