4.3: Graphing Using Intercepts
Learning Objectives
At the end of this lesson, students will be able to:
 Find intercepts of the graph of an equation.
 Use intercepts to graph an equation.
 Solve realworld problems using intercepts of a graph.
Vocabulary
Terms introduced in this lesson:
 intercepts

x− intercept,y− intercept  standard form
 coefficients
 initial cost
Teaching Strategies and Tips
One way to graph lines is by plotting intercepts. Additional questions to ask students in the introduction:

Do all lines have
x andy− intercepts?
Solution: No.
 Which lines have only one intercept?
Solution: Horizontal and vertical lines.
 Is it possible for lines not to have intercepts?
Solution: No, every line must have at least one intercept.

Is it possible for lines to have more than
2 intercepts?
Solution: Yes, but infinitely many intercepts. The lines
In Examples 2a and 2b, have students convert their fractions into decimals before plotting.
Use the coverup method as a quick way to find intercepts algebraically.
In Examples 4 and 5, encourage students to interpret the meaning of the intercepts in context of the problem.
Error Troubleshooting
General Tip: Students will often attempt to find an
In Example 4, distinguish between the independent and dependent variables first. To find an appropriate scale for the axes, determine the domain of the independent variable next.
In Example 5, although “without spending more than