Class

Practice

7-1

Form G

Exploring Exponential Models

1 x

3. y 5 2 Q 5 R

Graph each function.

1. y 5 (0.3)x

6

Date

2. y 5 3x

y

6

y

y

4

4

2

2 x x

Ϫ2 O

2

Ϫ2 O

2

x

Ϫ2 O

1

4. y 5 2(3)x

5. s(t) 5 2.5t

y

6 s(t)

6 f(x)

4

2

4

6

4

1

6. f (x) 5 2(5)x

2

2

2

Ϫ2 O

x

t

x

2

1 x

7. y 5 0.99 Q 3 R decay; 0.99

Ϫ2 O

Ϫ2 O

2

2

Without graphing, determine whether the function represents exponential growth or exponential decay. Then find the y-intercept.

5 x

9. y 5 185 Q 4 R growth; 185

2 1 x

10. f (x) 5 3 Q 2 R decay; 2

3

8. y 5 20(1.75)x growth; 20

1 6 x

12. y 5 5 Q 5 R growth; 1

5

11. f (x) 5 0.25(1.05)x growth; 0.25

13. Suppose you deposit $1500 in a savings account that pays interest at an annual

rate of 6%. No money is added or withdrawn from the account.

a. How much will be in the account after 5 years? about $2007.34

b. How much will be in the account after 20 years? $4810.70

c. How many years will it take for the account to contain $2500? about 9 years

d. How many years will it take for the account to contain $4000? about 17 years

Write an exponential function to model each situation. Find each amount after the specified time.

14. A population of 1,236,000 grows 1.3% per year for 10 years. y 5 1,236,000(1.013)x ; about 1,406,413

15. A population of 752,000 decreases 1.4% per year for 18 years. y 5 752,000(0.986)x ; about 583,448

16. A new car that sells for $18,000 depreciates 25% each year for 4 years. y 5 18,000(0.75)x ; $5695.31

Prentice Hall Gold Algebra 2 • Teaching Resources

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3

Name

7-1

Class

Date

Practice (continued)

Form G

Exploring Exponential Models

For each annual rate of change, find the corresponding growth or decay factor.

17. 145% 1.45

18. 210% 0.9

19. 240% 0.6