Title: Slopes and Intercepts
1Slopes and Intercepts Lesson 1.2
y mx b ax by c
2Objectives
Glossary Terms
- Graph a linear equation.
- Write a linear equation for a given line in the
coordinate plane.
slope of a line slope-intercept form standard
form horizontal line vertical line x-intercept y-i
ntercept
3Slopes of lines
4SLOPE OF A LINE
The slope, or steepness of a line, is the ratio
of the change in y to the change in x or It
is often called the rise over the run.
?y ?x
5Rules and Properties
Slope of a line
Point 1 (x1, y1) Point 2 (x2, y2) slope m
6FIND THE SLOPE
of the line through points (7,2) and (1,1)
1/6
of the line containing the points (3, 5) and
(-2, -6)
11/5
of the line containing the points (-5, 3) and
(3, -4)
-7/8
7Exploring Slopes
Graph each pair of equations. Describe how the
slopes are alike and how they are different.
Y x and y x
Y x and y x
8y x and y -x
y x and y x
Make a conjecture about the slopes of y mx when
m lt 0 and when m gt 0.
9Puff! Puff! Positive Slope
10Wheee! Negative Slope
11Exploring Slopes
Find the slope of the line containing the points
(-3, 3) and (2, 3).
The slope is 0
The graph of a line with zero slope is a
horizontal line.
(2, 3)
(-3, 3)
12Find the slope of the line containing the points
(-2, 1) and (-2, 3)
The slope is 2/0 (undefined)
The graph of the line with undefined slope is a
vertical line
(-2, 3)
(-2, 1)
13YawnZzzzzzz Zero Slope
14Yikes! No Slope!
15MATCH THE SLOPE
a
1. Positive 2. negative 3. 0 slope 4. no slope
(or undefined slope)
b
c
d