3.5 graphing linear equations in slope-intercept form

3.5 Graphing Linear

Equations in Slope-Intercept

Form

Do Now• Graph 2x + 4y = 8. Find the

intercepts.

Slope• The slope m of a nonvertical line

passing through two points (x1, y1) and (x2,y2) is the ratio of the rise to the run.

Example 1

Example 2

Example 3

Example 5• What is the slope of the line?

4 Types of Slope• Positive Slope

o The line rises from left to right.

• Negative Slopeo The line falls from left to right.

• Slope of 0o The line is horizontal.

• Undefined Slopeo The line is vertical.

Slope-Intercept Form• Slope-intercept form is written as y= mx + b.

A linear equation written in the form y = 0x + b is a constant function.

Steps to Using Slope-Intercept Form to

GraphA)Solve for y.B)Find the slope and the y-

intercept.C)Plot the y-intercept.D)Use the slope to find another

point on the line.

Example 6Graph 2x + y = 2.

Example 7Graph y = 4x – 4.

Example 8• A submersible that is exploring the ocean

floor begins to ascend to the surface. The elevation h (in feet) of the submersible is modeled by the function h(t) = 650t – 13,000, where t is the time (in minutes) since the submersible began to ascend.

a) Graph the function and identify its domain and range. b) Interpret the slope and intercepts of the graph.