### Unit 5: Graphs of Linear Equations and Inequalities

This unit is an introduction to graphing relationships between the two quantities on the coordinate plane. A graph helps visualize how one quantity depends on another. In this course, you will only graph relationships that can be described by a linear equation, and their graphs are always straight lines. Graphing is an important tool that aids in analyzing relationships, both in abstract and in applied math. The material in this unit will help you become comfortable with graphing pairs of numbers on the coordinate plane and understand how the equations and relationships can be represented by lines. As an example, you might want to graph how the location of a train depends on the time since the train departed from the station. If the train is moving with constant speed, this graph would be a straight line. The slant of this line (which, as you will learn in this unit, is called the slope) will depend on the speed: the greater the speed, the steeper the line. If the line is going up (looking from left to right), it tells you that the distance is growing with time, which means that the train is moving away from the station. Otherwise, if the line is going down, it tells you that the distance is decreasing, which means that the train is approaching the station. You will see that a lot of information about the train's journey can be gathered from just one graph.

**Completing this unit should take you approximately 21 hours.**