1. Do Now: If you did not yesterday, put your worksheet in the basket
$6500 principle earning 2.8% compounding monthly after 2 years
$2000 principle earning 5.4% compounding semiannually after 4 years

2. Exponential Growth & Decay

3. Standard Form:
y = a•bx
However, depending on the question, we have to change the growth factor.

4. (that’s a really small number)
The number of students enrolled at a college is 15,000 and grows 4% each year. After 25 years, what can we predict the number of students enrolled in college will be?
Usually we would write it like this:
y = 15,000(.04)25
y = x 10-31
(that’s a really small number)
However, the number of students enrolled is suppose to grow…dose this answer make sense?

5. Exponential Growth: A = the balance
P = principle (initial/starting amount)
r = the annual interest rate (decimal)
t = the time

6. Does this answer make sense?
The number of students enrolled at a college is 15,000 and grows 4% each year. After 25 years, what can we predict the number of students enrolled in college will be?
Now with the new formula we write it like this:
A = 15,000(1+.04)25
A = 15,000(1.04) 25
A= 39,987 students enrolled
Does this answer make sense?
YES!

7. With Exponential Growth, we also have Exponential Decay

8. What is the difference between growth and decay??
Exponential Decay:
A = the balance
P = principle (initial/starting amount)
r = the annual interest rate (decimal)
t = the time
What is the difference between growth and decay??

9. Exponential Decay
You buy a new computer for college costing $2100. The computer decreases by 30% annually. What will the price of the computer be after four years of college?

10. How to know when to use which formula…
What are some key words we can look for within word problems to decide?
Exponential Growth
Exponential Decay
Growing
Increasing
Appreciates
Decreases
Depreciates
Goes down

11. By looking at an equation, how can we tell if the function is exponential growth and exponential decay?
A = P( )t
We look here
rate > 1…..growth
rate < 1…..decay

12. Growth or Decay? A = 16(1.025)5 A = 45(.45)15 A = 2500(.005)x

13. Growth & Decay Worksheet
Complete the worksheet. You will find the answers around the room. Find the answer and write the letter in the spaces to spell something.