Suppose two mice live in a barn. If the number of mice quadruples every 4 months, how many mice will there be in 2 years?

8.1 Graphing

Exponential Functions

Exponential Functions

y = a∙bx

Where a = , b =

Used to model __________________

and _______________________

Example 1. Graph y = 2 ∙ 3x

x y

Example 2. Determine whether each function models

exponential growth or exponential decay. Then find the growth or decay factor.

a. y = 100(.12)x

b. y = 0.2(5)x

c. y = 16( ½ )x

Example 3.

In 2000, the annual rate of increase in US population was 1.24%.

c. Predict the population in 2015.

d. Why might this not be valid?

a. Find the growth rate.

b. Write a function to model the growth.

http://www.census.gov/population/www/popclockus.html

The exponential decay graph shows the expected depreciation for a car over four years. Estimate the value of the car after six years.

Example 4.