# Chapter 4: Linear Functions

**Advanced**Created by: CK-12

## Introduction

Here you'll learn all about lines. You will learn how to find the slope of a line and the equation of a line. You will learn to graph a line directly from its equation without first having to make a table. You will learn about parallel and perpendicular lines and their relationship with slope. Finally, you will learn how to use your knowledge of lines to model and solve real-world problems.

- 4.1.
## Slopes of Lines from Graphs

- 4.2.
## Slopes of Lines from Two Points

- 4.3.
## Equations of Lines from Two Points

- 4.4.
## Graphs of Lines from Equations

- 4.5.
## Equations of Lines from Graphs

- 4.6.
## Equations of Parallel and Perpendicular Lines

- 4.7.
## Applications of Linear Functions

### Chapter Summary

## Summary

You learned that slope is a measure of the steepness of a line. You learned how to find the slope of a line given two points on the line or the graph of the line. You also learned how to write the equation of a line in two forms: slope-intercept form and standard form. You learned how to graph a line directly from its equation without first making a table.

You also learned about parallel and perpendicular lines. You learned parallel lines always have the same slope while perpendicular lines always have slopes that are opposite reciprocals. Finally, you learned how to model real-world problems with linear functions.