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Name ——————————————————————— Date ————————————
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right
© H
ough
ton
Miffl
in H
arco
urt P
ublis
hing
Com
pany
. All
right
s re
serv
ed.
Practice CFor use with the lesson “Write and Graph Exponential Growth Functions”
Write a rule for the function.
1. x 22 21 0 1 2
y 2 1 }
16 2
1 } 4 21 24 216
2. x 21 0 1 2 3
y 5 } 2 5 10 20 40
Graph the function and identify its domain and range.
3. y 5 15x 4. y 5 (2.25)x 5. y 5 (5.2)x
x
y
3
9
15
12123
23 3
x
y
1
3
12121
23
23 3
x
y
1
3
5
12121
23 3
6. y 5 1 9 } 8 2
x 7. y 5 27x 8. y 5 2 1 5 }
2 2
x
x
y
1
3
12121
23
23 3
x
y
12121
23
25
27
23 3
x
y
1
3
12121
23
23 3
9. y 5 3 p 6x 10. y 5 4 p 1 3 } 2 2
x 11. y 5 22 p 4x
x
y
3
9
15
2312123 3
x
y
2
6
10
12122
23 3
x
y2
12122
26
210
23 3
Algebra 1Chapter Resource Book7-44
Lesson
7.4
Les
so
n 7
.4
CS10_CC_A1_MECR710730_C7L04PC.indd 44 5/13/11 11:43:23 PM
Name ——————————————————————— Date ————————————Co
pyrig
ht ©
Hou
ghto
n M
ifflin
Har
cour
t Pub
lishi
ng C
ompa
ny. A
ll rig
hts
rese
rved
.
Graph the function. Compare the graph with the graph of y 5 5x.
12. y 5 2 p 5x 13. y 5 25x 14. y 5 1 }
2 p 5x
x
y
2
6
10
12122
23 3
x
y
1
12121
23
25
23 3
x
y
1
3
12121
23
23 3
15. y 5 23 p 5x 16. y 5 2 1 }
2 p 5x 17. y 5 2
3 }
4 p 5x
x
y3
12123
29
215
23 3
x
y
1
3
12121
23
23 3
x
y
1
3
12121
23
23 3
18. Investments You deposit $375 in a savings account that earns 2.75% interest compounded yearly. Find the interest earned by the account after the given amounts of time. Explain how you got your answers.
a. 1 year
b. 5 years
c. 20 years
19. Population A town had a population of 65,000 in 2000. Then the population increased by 2.5% each year for the next 5 years.
a. Write a function that models the population over time.
b. Use the function to predict the population in 2004.
20. Internet Users The number of students who have applied for Internet privileges at school has doubled each month.
a. What is the percent of increase each month?
b. Ten students had applied for Internet privileges initially. Write a function that models the number of students applying for Internet privileges over time.
c. How many students will have applied for Internet privileges in 4 months?
Practice C continuedFor use with the lesson “Write and Graph Exponential Growth Functions”
Algebra 1Chapter Resource Book 7-45
Less
on
7.4
Lesson
7.4
CS10_CC_A1_MECR710730_C7L04PC.indd 45 5/13/11 11:43:24 PM
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© H
ough
ton
Miffl
in H
arco
urt P
ublis
hing
Com
pany
. All
right
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serv
ed.
Lesson Write and Graph Exponential Growth Functions, continued12.
x
y
2
6
10
1212322
3
13.
x
1
12321
23
25
3
y
vertical stretch reflection in x-axis
14.
x
1
3
5
1212321
3
y 15.
x
3
1212323
29
215
3
y
vertical shrink vertical stretch and reflection in x-axis
16.
x
1
1212321
23
25
3
y 17.
x
2
1212322
26
210
3
y
vertical shrink and vertical stretch and reflection in x-axis reflection in x-axis
18. a. $512.50 b. $565.70 c. $819.31 19. y 5 8000(1.07)t 20. a. y 5 10,000(1.08)t b. $19,990.05
Practice Level C
1. y 5 24x 2. y 5 5 p 2x 3.
x
y
3
9
15
12123
23 3
domain: all real numbers; range: all positive real numbers
4.
x
y
3
12121
23
23 3
domain: all real numbers; range: all positive real numbers
5.
x
y
1
3
5
12121
23 3
domain: all real numbers; range: all positive real numbers
6.
x
y
3
12121
23
23 3
domain: all real numbers; range: all positive real numbers
7. x
y
12121
23
25
27
23 3 domain: all real numbers; range: all negative real numbers
8.
x
y
1
3
1
23
23 3
domain: all real numbers; range: all negative real numbers
9.
x
y
3
9
15
12123
23 3
domain: all real numbers; range: all positive real numbers
10.
x
y
2
6
10
12122
23 3
domain: all real numbers; range: all positive real numbers
11.
x
y2
122
26
210
23 3
domain: all real numbers; range: all negative real numbers
Algebra 1Chapter Resource BookA6
7.4
an
sw
er
s
CS10_CC_A1_MECR710730_C7AK.indd 6 5/21/11 2:24:19 AM
Copy
right
© H
ough
ton
Miffl
in H
arco
urt P
ublis
hing
Com
pany
. All
right
s re
serv
ed.
Lesson Write and Graph Exponential Growth Functions, continued12.
x
y
2
6
10
12122
23 3
13.
x
y
1
121
23
25
23 3
vertical stretch reflection in x-axis
14.
x
y
1
3
12121
23
23 3
15.
x
y3
123
29
215
23 3
vertical shrink vertical stretch and reflection in x-axis
16.
x
y
1
3
12121
23
23 3
17.
x
y
1
3
121
23
23 3
vertical shrink and vertical shrink and reflection in x-axis reflection in x-axis
18. Subtract the amount deposited from the balance. a. $10.31 b. $54.48 c. $270.16
19. a. y 5 65,000(1.025)t b. about 71,748 people
20. a. 100% b. y 5 10(2)t c. 160 students
Study Guide
1. y 5 9 p 3x
2.
2123 1 3
1
5
7
x
y 5 4(3)x
y domain: all real numbers; range: all positive real numbers
3. 23 1 3
25
27
y 5 25(6)x
x
y
Because the y-values for y 5 25 p 6x are 25 times the corresponding y-values for y 5 6x, the graph of y 5 25 p 6x is a vertical stretch and reflection in the x-axis of the graph of y 5 6x.
Problem Solving Workshop: Worked Out Example
1. $389.78 2. The value raised to the x power should have been 1 1 0.36; and the final calculation of 0.10 is also incorrect. The spending per person per year on the Internet in 2007 was $389.78.
3. y 5 179,323,175(1.011)x; 309,880,465
4. 7.59 feet 5. 16.41 feet
Challenge Practice
1. y 5 3x 2. y 5 3 p 2x 3. y 5 1 } 2 p 5x
4. y 5 1 1 } 9 2 3x or y 5 3x 2 2 5. y 5 1 3 }
2 2 2x or
y 5 3 p 2x 2 1
6. f (x) 5 3 p 28x and g(x) 5 3 p 212x, so g(1) > f (1)
7. f (x) 5 1 }
2 p 16x and g(x) 5 1280 p 16x,
so g(1) > f (1)
8. f (x) 5 25 p 52x and g(x) 5 52x, so f (1) > g(1)
9. f (x) 5 6 p 42x and g(x) 5 1 }
2 p 43x, so
f (1) > g(1) 10. f (x) 5 1000 p (1.5)10x and g(x) 5 2000 p (1.5)3x, so f (1) > g(1)
Lesson Write and Graph Exponential Decay Functions
Teaching Guide
1. Computers decrease in value over time because they have a set useful life and newer and better computers are produced each year.
2. $800; To determine how much the computer decreased in value, you multiply the intitial cost $1000, by the rate 20%. Then you subtract this from the intial cost of $1000 to determine the value of the computer after 1 year. 3. $640, $512, $409.60, $327.68
Algebra 1Chapter Resource Book A7
7.4
an
sw
er
s
7.5
CS10_CC_A1_MECR710730_C7AK.indd 7 5/21/11 2:24:20 AM
