1. Exponential Growth and Decay Formula:
Initial Starting Value
# of times it grows or decays
Growth/Decay Factor

2. Exponential Growth
Growth Factor: b = 1 + Rate of Growth
$10 is invested in a savings account where is grows 5% per year.
What is the y –intercept?

3. Exponential Decay
Decay Factor: b = 1 - Rate of Growth
10 grams of a particular liquid decays at a rate of 75% per day.

4. Practice: Monthly benefits for Social Security in May were $23,307 million. Since then, benefits have increased about 5.4% per year.
a) Write an exponential function to model the growth of monthly Social Security benefits paid each year. (use millions in your answer!)
y = 23,307( )x  y = 23,307(1.054)x
b) If benefits continue to grow at this rate, when will the monthly Social Security benefits reach $50,000 million?
50,000 = 23,307(1.054)x
Graph y = 23,307(1.054)x
and y = 50,000
2) Solve = 1.054x
through guess and check

5. There is 81% of the fund LEFT each year
In 1984, funds for the Emergency Food Assistance program were about $1,075 million. Since 1984, this fund has decreased about 19% per year.
a) Write an exponential function to model this situation.
Y= 1,075( )x  y = 1,075(0.81)x
There is 81% of the fund LEFT each year
b) Estimate the funds available for the Emergency Food Assistance program this year.
Y = 1075(0.81)24  million
Or graph the equation and TRACE with x = 24