1. The Equation of a Line
Slope-Intercept Form

2. The Equation of a Line
The equation of a line in slope-intercept form is
SLOPE
Y-INTERCEPT

3. Examples:
Find the slope (m) and the y-intercept (b) of the following equations.
2. Write the equation of the line given the slope (m) and the y-intercept (b).

4. The Roles of Slope and the Y-intercept
Slope (m)
Tells you two things:
Direction
If the slope is positive, the line is increasing (goes up and to the right).
If the slope is negative, the line is decreasing (goes down and to the right).
Steepness
The larger the number for slope, the steeper the line.
The smaller the fraction for the slope, the flatter the line.
Y-intercept (b)
Tells you where the line crosses the y-axis.

5. Examples
Without graphing, determine which equation has the graph with the steepest line.

6. Graphing a Line using Slope and Y-intercept
up or down (if negative)
right
How to graph a line using slope and y-intercept:
Identify m and b.
Plot the y-intercept (b).
From the slope (m), identify the rise and run.
From the y-intercept (b) use the rise and run from the slope (m) to plot the next point.
Draw a line, passing through the y-intercept and the point.

7. Examples:
Use the slope and y-intercept to graph each line.

8. Examples (continued):
Use the slope and y-intercept to graph each line.

9. Homework
Handout #1
Handout #2
*Make sure you have a ruler!