Download presentation

Presentation is loading. Please wait.

1
**4.2 Exponential Decay Functions**

Retesting Opportunity: Dec. 1 Quiz: Dec. 3 Performance Exam: Dec. 4

2
Vocabulary An exponential decay function has the form y = abx, where a > 0 and 0 < b < 1. The base b of an exponential function is called the decay factor. The time required for a substance to fall to half its initial value is called half-life.

3
Example 1: Graph y = (1/2)x

4
Example 2: Graph y = -3(2/5)x

5
Example 3: Graph y = 3(1/2)x+1 – 2

6
**Vocabulary Exponential Decay Model**

The amount y of the quantity after t years can be modeled by the equation y = a(1 – r)t, where a is the initial amount and r is the percent decrease expressed as a decimal. Note that the quantity 1 – r is the decay factor.

7
Example 4: The rate at which caffeine is eliminated from the bloodstream is about 15% per hour. An adult drinks a caffeinated soda, and the caffeine in his or her bloodstream reaches a peak level of 30 milligrams. Predict the amount, to the nearest tenth of a milligram, of caffeine remaining 1 hour after peak and 4 hours after the peak level.

8
Solution: In growth to obtain the growth factor we added our rate, so exponential decay we _________ the rate of decay from 100%. What is our decay factor? Write the expression for the caffeine level x hours after the peak level. 30(.85)x 85% or 0.85

9
Solution continued: What is the amount of caffeine remaining after 1 hour? 25.5 milligrams After 4 hours? 15.7 milligrams

10
Homework: P. 137 #1-11odd P. 138 #10

Similar presentations

Presentation is loading. Please wait....

OK

6. 1 Exponential Growth and Decay

6. 1 Exponential Growth and Decay

© 2017 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Ppt on google glasses Topics for ppt on environmental problems Ppt on indian postal service Ppt on buddhism in india Ppt on causes of road accidents Ppt on condition based maintenance cbm Ppt on regional trade agreements in germany Ppt on omission of articles in english Ppt on principles of object oriented programming Ppt on acid-base titration formula