### Home > PC > Chapter 1 > Lesson 1.1.1 > Problem 1-6

All of the equations in the previous problem are functions. Describe what it means to be a “function.” Give equations of two non-functions and explain why these two examples are not functions.

A note on ICONS: You will see several different icons used in this course to designate a particular feature of the problem. They are:

The problem shows a particular feature of your calculator. |
Complete this problem without the use of your calculator. | ||

The problem shows you how to write a program for your calculator or asks you to write your own program. |
The problem contains important information that should be added to your Tool Kit. | ||

The problem is your opportunity to verify that you have learned this topic. |

Read the Math Notes box in this lesson.