Page 549 - Algebra 1

Example
4
Application: Dog Breeds
The table shows the average number of American Kennel Club registrations (rounded to the nearest 100) for Bernese mountain dogs and rottweilers.
American Kennel Club Registrations, 2002–2006
If the trend continues, in which year will the number of registered Bernese mountain dogs be equal to or exceed the number of registered rottweilers?
SOLUTION
Write an expression for the number of registered dogs for y years after 2006. Bernese mountain dogs: 3700 + 300y
rottweilers: 14,700 - 1900y
Breed
2006 Registrations
Average Yearly Change
Bernese Mountain Dogs
3700
300
Rottweilers
14,700
-1900
3700 + 300y ≥ 14,700 - 1900y 3700 + 2200y ≥ 14,700
2200y ≥ 11,000 y ≥ 5
Write an inequality.
Add 1900y to both sides. Subtract 3700 from both sides. Divide both sides by 2200.
Math Reasoning
Analyze In the year 2011, how does the number of rottweilers compare to the number of Bernese mountain dogs? Explain.
The solution y ≥ 5 does not answer the question. The variable y represents the years after 2006.
2006 + 5 = 2011
If the trend continues, the number of Bernese mountain dogs registered
will be equal to or exceed the number of rottweilers registered in 2011.
Lesson Practice
Solve and graph each inequality. a. 4x - 8 > -2x + 4
____ b. - 3a + 7 ≥ 2a - 9
(Ex 1) 5 10 5 10 Determine whether each inequality is always true, sometimes true, or never
true. If it is sometimes true, identify the solution set.
(Ex 3)
d. x+5+3x>4x+19 e. x+5>x-3
f. The table shows the average number of cell phone minutes used by
(Ex 4)
If the trend continues, in which month will Ara’s average minutes be equal to or greater than Lexi’s?
(Ex 1)
c. 4(x-1)-2x≤6-5(x+2) (Ex 2)
Ara and Lexi.
User
January Average
Average Change, January–May
Ara
4000
500
Lexi
12,000
-500
534 Saxon Algebra 1