Exponential functions tell the stories of explosive change. The two types of exponential functions are **exponential growth** and **exponential decay**. Four variables — percent change, time, the amount at the beginning of the time period, and the amount at the end of the time period — play roles in exponential functions.

Use this page to learn more about exponential functions.

### 1. What are Exponential Growth Functions?

When an original amount is increased by a consistent rate over a period of time, **exponential growth **is occurring. The purpose of this page is to use exponential growth functions to make predictions.

### 2. What are Exponential Decay Functions?

When an original amount is reduced by a consistent rate over a period of time, **exponential decay** is happening. The purpose of this page is to use an exponential function - exponential decay - to make predictions.

### 3. Exponential Growth and Percent Increase

When an original amount is increased by a consistent rate over a period of time, **exponential growth** is happening. The purpose of this page is to learn more about that consistent rate. The key to understanding exponential growth is learning about percent increase.

### 4. Exponential Decay and Percent Change

When an original amount is reduced by a consistent rate over a period of time, **exponential decay** is happening. The purpose of this page is to learn more about that consistent rate, the **decay factor**. The key to understanding the decay factor is learning about percent change.

### 5. Solving Exponential Growth Functions

Four variables — growth factor, time, the amount at the beginning of the time period, and the amount at the end of the time period — play a role in exponential functions. This article focuses on how to use exponential growth functions to find the amount at the beginning of the time period.

### 6. Solving Exponential Decay Functions

This article focuses on how to use an exponential decay function to find the amount at the beginning of the time period.