The graph shows album sales (which include
CD, vinyl, cassette, and digital albums) and
music purchases (which include digital tracks,
albums, singles, and music videos) in millions of
units from 2004 through 2008. Use the graph to
work Exercises 71 and 72.
71.Locate the line on the graph that represents
music purchases.
(a)Write two ordered pairs , where
x is the year and y is purchases in
millions of units, to represent the data
for the years 2004 and 2008.
(b)Use the ordered pairs from part (a) to
find the slope of the line.
(c) Interpret the meaning of the slope in the
context of this problem.
72.Locate the line on the graph that represents album sales. Repeat parts (a)–(c) of
Exercise 71.For part (a), xis the year and yis sales in millions of units.
1 x, y 2
210 CHAPTER 3 Linear Equations and Inequalities in Two Variables; Functions
0
400
800
1200
1600
2000
2004 2006 2008
Album
Sales
Music
817 Purchases
1513
Year
Source: Nielsen SoundScan.
Millions of Units
y
x
Music Ups and Downs
668
428
EXERCISES 73–76
Some graphing calculators have the capability of
displaying a table of points for a graph. The table shown
here gives several points that lie on a line designated
73.Use any two of the ordered pairs displayed to find the
slope of the line.
74.What is the x-intercept of the line?
75.What is the y-intercept of the line?
76.Which one of the two lines shown is the graph of
A. B.
Y 1?
Y 1.
TECHNOLOGY INSIGHTS
10
10
10
Solve each equation for y.See Section 2.5.
- 8 x= 8 - 2 y 81.y- 1 - 82 = 21 x- 42 82.y- 3 = 43 x- 1 - 624
2 x+ 5 y= 15 - 4 x+ 3 y= 8 10 x= 30 + 3 y
PREVIEW EXERCISES
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