1. Objectives
Graph lines and write their equations in slope-intercept form.
Classify lines as parallel, intersecting, or coinciding.

2. Vocabulary
point-slope form
slope-intercept form

4. Example 1A: Writing Equations In Lines
Write the equation of each line in the given form.
the line through (–1, 0) and (1, 2) in slope-intercept form

5. Example 1B
Write the equation of each line in the given form.
the line with slope 0 through (4, 6) in slope-intercept form

6. Example 2A
Graph each line.
y = 2x – 3

7. Example 2B
Graph each line.
y = –3

8. A system of two linear equations in two variables represents two lines
A system of two linear equations in two variables represents two lines. The lines can be parallel, intersecting, or coinciding. Lines that coincide are the same line, but the equations may be written in different forms.

10. Example 3A: Classifying Pairs of Lines
Determine whether the lines are parallel, intersect, or coincide.
y = 3x + 7, y = –3x – 4

11. Example 3B: Classifying Pairs of Lines
Determine whether the lines are parallel, intersect, or coincide.

12. Example 4: Problem-Solving Application
Erica is trying to decide between two car rental plans. For how many miles will the plans cost the same?