1. Interpreting Parts of Exponentials in Context
EOC Review:
Interpreting Parts of Exponentials in Context

2. initial value (y-intercept) rate of change
EXPONENTIAL FUNCTION
y = a(b)x
initial value (y-intercept) rate of change

3. initial value (y-intercept) rate of change
GROWTH & DECAY
y = a(1± r)x
initial value (y-intercept) rate of change
+ growth (more than 1.00)
- decay (less than 1.00)

4. Example: E#3.1 How do we know it is exponential?
Where do we find the percent rate of change?
How do we know it is growth or decay?
The function f(x) = 20,000(1.08)x models the population
of a town where x is the number of years since 2005.
Which statement is true about the population of the town?
A. The population of the town is decreasing at a rate of 12% per year.
B. The population of the town is decreasing at a rate of 8% per year.
C. The population of the town is increasing at a rate of 12% per year.
D. The population of the town is increasing at a rate of 8% per year.

5. Example E#3.2
How do we know this is exponential?
The size of a population of a town can be modeled by the function P = 20,000(1.08)x, where x is the number of years since What does 20,000 represent in this function?
Is the 20,000 the
y-intercept or the percent rate of change?

6. You Try! Examine the parts of the function. Ask:
What is the initial value?
Is the rate growth or decay?

7. Check it E#3.3
A fungus is growing in a petri dish. The fungi count for t days since the lab started is modeled by the function f(x) = 4(1.2)t . At what rate is the population increasing each day?

8. Check it: E#3.4
The function f(t) = 500(0.8)t models the size of a population of fish in a pond t years after it was first stocked in What does 500 represent in this function?

9. Check it: E#3.5
Animal control estimated that there is a population of feral cats150 growing at a rate of 15% per year, t. Write an equation models the population of cats over the years?

10. Check it E#3.6
The equation y = 550(1.05)x models the value of an investment after x years. Which statement is true about the value of the investment?
A. The value of the investment is growing by $550 each year.
B. The value of the investment is growing by 5% each year.
C. The value of the investment is decreasing by $550 each year.
D. The value of the investment is decreasing by 5% each year.