Page 98 - Math Course 3 (Book 1)

Slope of a Line

Mo. 3

Lesson 5 Let’s Begin

KEY CONCEPTS:
1. Use rise and run to find the slope of a line. Use Rise and Run to Find Slope
2. Use a graph to find slope.
3. Find and compare the slope of a line.
Example

HILLS
MO. 3 - L5a Find the slope of a hill that rises 30 feet for every
horizontal change of 150 feet.
Finding the Slope of a Line slope = rise Write the formula.
run
30 feet rise = 30 feet, run = 150 feet
=
Vocabulary A-Z 1 150 feet Simplify.
Let us learn some vocabulary = 5

1
Answer The slope of the hill is or 0.2.
5
slope

describes the steepness of a line. It is the ratio
of the rise (vertical change) to the run (horizontal Use a Graph to Find Slope
change).
Examples
rise vertical change
slope =
run horizontal change
Given two points: Find the slope of the line.
(x , y ) (x , y )
1 1 2 2
Slope Formula:
y – y
2
m = x – x 1
2 1

Concept Summary
Slope

Words The slope m of a line passing through m = y – y 1 Definition of slope
2
points at (x , y ) and (x , y ) is the ratio of x – x 1
2
2
1
2
1
the difference in y-coordinates to the 4 – 1 (x , y ) = (0, 1)
corresponding difference in x-coordinates. m = 1 1
1 – 0 (x , y ) = (1, 4)
2
2
Symbols Model m = 3 or 3
y – y y 1
2
m = x – x 1 where x ≠ x 1
2
2 1 x – y 1
1
Answer The slope is 3.
x , y
2 2
x
0
90