# Slope

## Objectives

This unit has been divided into four sections. The first section is this introduction to slope. After this follows three more sections, each of which provides you with practice problems.

After reviewing the entire unit you will be able to:

• Define slope.
• Calculate the slope of a straight line from its graph.
• Be able to identify if a slope is positive, negative, zero, or infinite.
• Identify the slope and y-intercept from the equation of a line.
• Identify the y-intercept from the graph of a line.

## What is Slope?

The slope is used to tell us how much one variable (y) changes in relation to the change of another variable (x). This can also be written in the form shown on the right.

Let's go back to the pizza example introduced in the first unit. As you may recall, a plain pizza with no toppings was priced at 7 dollars. As you add one topping, the cost goes up by 75 cents.
 In the case of our pizza example the slope is given in the equation on the right. If you think about this, the price of a pizza does change at a rate of 75 cents for each one topping added. Now let's look at different ways to calculate the slope of relationships.