1. Today’s Agenda
• Attendance / Announcements
– Exam 1 – Tuesday 9/24
• Covers Chapters 1.1 to 2.4 (skip 2.5)
• Project 1
• Questions from HW?
• Section 2.2b, 2.3

2. Quick Review
Write the following equation in slope-intercept form
752 yx

3. Slopes…continued
Find the slope of the
line through the points
(-4, 2) and (3, 2)
So, horizontal lines have a slope of….
And have an equation of….

4. Slopes…continued
Find the slope of the
line through the points
(-3, 2) and (-3, 6)
So, vertical lines have a slope of….
And have an equation of….

5. Slopes…continued
Parallel lines never
intersect. They have
the same slope.

6. Slopes…continued
Are the following pairs of lines parallel?
6
4
3
2
3
2
xy
xy
6
6
xy
xy
843
64
3
yx
xy

7. Slopes…continued
Perpendicular lines
meet at right angles.
They have slopes of
negative reciprocals.
Also, the product of the slopes of perpendicular
lines must equal -1

8. Slopes…continued
Are the following pairs of lines parallel,
perpendicular, or neither?
3
4
xy
xy

9. Slopes…continued
Are the following pairs of lines parallel,
perpendicular, or neither?
3
6
6
1
xy
y
4
1
2
3
3
2
4
xy
xy

10. Point-Slope Form (p. 94)
To find an equation of a line when you
have a point, and a slope

11. Point-Slope Form
Find the equation of the line with slope -3
through the point (-4, 1)
)( 11
xxmyy

12. Point-Slope Form
Find the equation of the line that passes
through the points (-1, -2) and (2, -1)
)( 11
xxmyy

13. Forms of Linear Equations (p. 95)

14. 2.3 Linear Modeling
General Idea / Steps
• Plot data onto a graph (scatterplot)
• Create “line of best fit” (linear model)
• Find equation of linear model
• Use to predict new or unknown
data

15. Year 2003 2004 2005 2006 2007
Profit 15.0 16.6 16.4 20.8 22.2
The profits of the General Electric Company (GE), in billions of
dollars, over a five-year period are shown in the following table.
Let x = 3 correspond to 2003. Plot the data.

16. Year 2003 2004 2005 2006 2007
Profit 15.0 16.6 16.4 20.8 22.2
What would you expect
the profit to be in 2010?
Remember, the x-value corresponds to the year. And
the y-value corresponds to the profit.

17. Year 2003 2004 2005 2006 2007
Profit 15.0 16.6 16.4 20.8 22.2
When would you expect
the profit to exceed $50 billion?
Remember, the x-value corresponds to the year. And
the y-value corresponds to the profit.

18. Classwork / Homework
Page 97
33 – 61 e.o.odd, 69
Page 108
1, 5, 7
Reviewing Lines Worksheet