8.1­8.2 Exponential Growth and Decay.notebook
March 25, 2013
8.1/8.2 ­ EXPONENTIAL GROWTH/DECAY
EXPONENTIAL FUNCTION
An exponential function has the form:
b is the KEY!
­if b > 1 Exponential Growth
­if 0 < b < 1 Exponential Decay
*Switched if the exponent is negative!*
EXAMPLES
State whether the function represents exponential growth
or exponential decay: .
Mar 15­2:02 PM
8.1­8.2 Exponential Growth and Decay.notebook
"REAL­LIFE PROBLEMS" ­ GROWTH/DECAY FACTOR
y = quantity after t years
a = initial amount
r = percent increase (+) or decrease (­)
t = number of years
(1 ± r) = "growth/decay factor" ­ after the r value
EXAMPLE
In 1990, the cost of tuition of UW­Madison was $4300. During
the next 8 years, tuition rose 4% each year.
(a) Write a model that displays this information
(b) Find the tuition in 1997
EXAMPLE
You buy a new car for $24,000. The value decreases by 16%
each year.
(a) Write a model that displays this information
(b) Find the value after 4 years
(c) When will the car have a value of $10,000?
HOMEWORK: p.470 #43­51(skip graphs)
p.477 #11­14,47­52 (skip graphs)
Mar 15­2:18 PM
March 25, 2013