# Section 4.4 – Exponential Equations and Growth

You might hear a person on the news talking about how some quantity is growing very rapidly. They might describe an epidemic as growing “exponentially”. Or the acres burned in a forest fire as growing “exponentially”. In these contexts, the term “exponential” is used to describe very rapid growth.

In mathematics, the term exponential can describe growth or decay. It might be rapid or not so rapid. The more important concept is that the change in the quantity occurs at a constant percent rate. If your bank account grows by 2% each year, it is growing exponentially. If the population of a country decreases by 1% each year, it is decaying exponentially.

In this section, our objectives are to

• Explain the differences among linear, quadratic, and exponential growth and decay.
• Use exponential equations to model growth and decay.
• Solve exponential equations using logarithms.

Use the workbook and videos below to help master these objectives.

Section 4.4 Workbook (PDF) 10/31/19

Section 4.4 Practice Solutions