SIMMS Exponential Functions
Fill-in the table:
Decimal
.13
Name: _____________________________________
Fraction
Percent
6.5%
2
5
1.75
42%
Find the percent increase or decrease for each pair of numbers.
ending value – starting value
Percent Change =
starting value
a.) Rose’s house on Rodeo Drive was valued at $1,060,000 in 2008. The same house sold for $4,250,000 in 2013. What was the percent increase in the value of the house? b.) A store sells 6,000 albums in January 2013 and 8,000 albums in November 2013. What was the percent increase in album sales over this time period? c.) Greece’s annual debt was $500 billion in 2009 and $475 billion in 2010. Calculate the percent decrease. An exponential function is in the form y = abx.
If you want to break it into more detail y = a(1±r)x.
Using these equations. What does the quantity (1±r) equal? The initial amount is “a” The growth factor is “b” The percent increase/decrease is the constant ratio (multiplier) If a function is exponential growth, add the constant ratio.to 1. If a function is exponential decay, subtract the constant ratio from 1 For each function, identify the initial amount, the constant ratio, the growth factor, fill in the
table and graph your results.
y = 20(1.03) x initial amount constant ratio growth factor -1
0
1
2
3
4
10
20
y = 1040(1.14) x initial amount constant ratio growth factor -2
-1
0
1
2
4
9
QUESTIONS:
What is the y-intercept?
What is the x-intercept?
Do these two equations represent growth or decay? Explain.
Will the value of the dependent variable(y) ever be negative? Explain.
What does n0 equal?
What does (4x + 3y –12)0 equal?
Word Problem:
Pennrose Gazette, the local newspaper for Pennrose County, is experiencing a reduction in
circulation. These days, the Gazette's audience increasingly prefers the Internet for news.
In 2008, the Pennrose Gazette counted 20,000 readers. The publisher predicts that its
readership will decrease by 10% each year. Use this information to answer the following
questions.
1. What was the original number of readers (a)?
2. What is the decay factor (b)?
3. Write a function describing the diminishing number of Pennrose Gazette readers.
4. . Based on the function, predict the number of readers in 2015.
5. Based on the function, predict the number of subscribers in 2028.