Intermediate Algebra – Student Workbook – Second Edition 2013

Lesson 3b – More Exponential Functions
Mini-Lesson
Problem 7 YOU TRY – WRITING EXPONENTIAL GROWH/DECAY MODELS
Given what we have covered in this lesson so far, you should now be able to quickly write
models for exponential growth or decay given a starting value and a rate of growth or decay. Fill
in the table below to practice. The first few are done for you.
Given
Initial population =
12,000
Growth rate = 40%
Initial
Value
(a value)
Growth or Decay
Factor
(b value)
12,000 40% = 0.40
b = 1 + .40 =1.40
Exponential Function
y=ab t
P(t) = 12,000(1.40) t
Initial value = 45
Decay rate = 35%
45 35% = 0.35
b=1 - 0.35=0.65
V(t)=45(0.65) t
Initial population = 145
Growth rate 3%
Initial value = 314
Decay rate 96.5%
Initial population = 412
Growth rate 13.24%
Initial investment = 546
Decay rate 2%
Initial amount = 3
Decay rate 22%
Initial population = 3061
Growth rate 205%
Scottsdale Community College Page 129 Intermediate Algebra