1. Warm Up 1.Quiz: Exponents & Exponential Functions 2.In the Practice Workbook, Practice 8-8 (p. 110) #1, 3, 5

2. Questions ?

3. Exponential Decay Starting Amount (when x = 0) Decay Factor

4. b = 1 – rate of decay (as a decimal)

5. Writing an Equation for Exponential Decay The value of a car is $20,000 and is depreciating at a rate of 12% per year.

6. Writing an Equation for Exponential Decay The population of a town of 18,000 is decreasing at a rate of 4% per year.

7. Writing an Equation for Exponential Decay The amount of a 20 mg dose of a antibiotic decreases in your bloodstream at a rate of 16% per hour.

8. Writing an Equation for Exponential Decay An investment of $8000 losses value at a rate of 2% per year.

9. Half Life

10. Half Life Formula Initial Amount Decay Factor Amount Remaining Number of Half Lives

11. Example: Half Life Fluorine-20 has a half-life of 11 seconds. Find the amount of Fluorine-20 left from a 40 gram sample after 44 seconds.

12. Example: Half Life Cesium-137 has a half-life of 30 years. Find the amount of Cesium-137 left from a 100 milligram sample after 180 years.

13. Example: Half Life Bismuth-214 has a half-life of 20 minutes. Find the amount of Bismuth-214 left from a 30 gram sample after 1 hour.

14. Example: Half Life Mendelevimu-258 has a half-life of 52 days. Find the amount of Mendelevimu-258 left from a 44 gram sample after 156 days.

15. Assignment In the textbook… pp. 442-441 #22 – 30, 32, 20, 21

16. Practice! In the Practice Workbook… Reteaching 8-8 (p. 109) # 4 – 6