1. Section 3.3 and Section 4.4
Algebra 1

2. Learning Targets Define rate of change and slope
Calculate and interpret rate of change in a context
Determine if a function is linear
Calculate the slope from a graph and coordinate points
Identify generalized slope patterns
Define & recognize parallel lines
Define & recognize perpendicular lines

3. Slope
𝑚= 𝑦 2 − 𝑦 1 𝑥 2 − 𝑥 1
where m represents the slope between two points 𝑥 1 , 𝑦 1 𝑎𝑛𝑑 ( 𝑥 2 , 𝑦 2 )
Describes the steepness of a line
Also known as rate of change

4. Finding Slope Ex 1: Find the slope between (-3, 4) & (2, -3)
−3−4 2−−3 =− 7 5

5. Finding Slope Ex 2: Find the slope between (-3, -1) & (2, -1)
−1−−1 2−−3 = 0 5 =0

6. Finding Slope Ex 3: Find the slope between (-2, 4) & (-2, -3)
−3−4 −2−−2 =− 7 0 =𝑢𝑛𝑑𝑒𝑓𝑖𝑛𝑒𝑑

7. Finding Slope
Find the slope of the following graph

8. Slope Summary
Positive Slope
Negative Slope
Undefined Slope
Zero Slope

9. Zero vs Undefined Visual

10. Identifying Slope Write your name in your notes.
Classify the slope of each segment of your name

11. Lines in the same plane that do not intersect & have the same slope
Parallel Lines
Lines in the same plane that do not intersect & have the same slope
Example:
Both lines have a slope of 1.

12. Perpendicular Lines
Lines in the same plane that intersect at right angles & have opposite reciprocal slopes
Example:
One line has a slope of
The other line has a slope of − 3 4 .

13. Identify Graphs: Parallel vs Perpendicular
Which of the following lines are parallel?
Which of the following lines are perpendicular?
A & C are perpendicular
D & E are parallel
B & D are perpendicular
B & E are perpendicular

14. Linear Functions
Linear functions have a constant rate of change/slope. In other words, the function has the same rate of change/slope between ANY two points

15. Rate of Change Examples
Rate of change is synonymous with slope. It is mostly referenced in “real life” situations.
$8.25/hour
6 miles/hour
9 people/min
$10/ticket

16. Number of Computer Games
Example 1 (PG 172 Ex. 1)
Use the table to find the rate of change. Then, explain its meaning.
Number of Computer Games
Total Cost ($) X Y 2 78 4
156 6
234
𝑐ℎ𝑎𝑛𝑔𝑒 𝑖𝑛 𝑦 𝑐ℎ𝑎𝑛𝑔𝑒 𝑖𝑛 𝑥 = 𝑐ℎ𝑎𝑛𝑔𝑒 𝑖𝑛 𝑑𝑜𝑙𝑙𝑎𝑟𝑠 𝑐ℎ𝑎𝑛𝑔𝑒 𝑖𝑛 𝑔𝑎𝑚𝑒𝑠
= 156−78 4−2 𝑜𝑟 234−156 6−4 = 78 2
= This represents that each game costs $39.

17. Google Survey
Tinyurl.com/Unit2-L1