Chapter 3.3

Slopes of Lines

Concept

Find the Slope of a Line

A. Find the slope of the line.

Substitute (–3, 7) for (x1, y1) and (–1, –1) for (x2, y2).

Answer: –4

Slope formula

Find the Slope of a Line

B. Find the slope of the line.

Substitute (0, 4) for (x1, y1) and

(0, –3) for (x2, y2).

Answer: The slope is undefined.

Slope formula

Find the Slope of a Line

C. Find the slope of the line.

Answer:

Slope formula

Substitute (–2, –5) for (x1, y1) and (6, 2) for (x2, y2).

Find the Slope of a Line

D. Find the slope of the line.

Answer: 0

Slope formula

Substitute (–2, –1) for (x1, y1) and (6, –1) for (x2, y2).

A.

B.

C.

D.

A. Find the slope of the line.

A. 0

B. undefined

C. 7

D.

B. Find the slope of the line.

A.

B.

C. –2

D. 2

C. Find the slope of the line.

A. 0

B. undefined

C. 3

D.

D. Find the slope of the line.

Concept

Example 2

Use Slope as Rate of Change

RECREATION In 2000, the annual sales for one manufacturer of camping equipment was $48.9 million. In 2005, the annual sales were $85.9 million. If sales increase at the same rate, what will be the total sales in 2015?

Concept

Example 3

Determine Line Relationships

Determine whether and are parallel, perpendicular, or neither for F(1, –3), G(–2, –1), H(5, 0), and J(6, 3).

Example 3

A. parallel

B. perpendicular

C. neither

Determine whether AB and CD are parallel, perpendicular, or neither for A(–2, –1), B(4, 5), C(6, 1), and D(9, –2)

Example 4

Use Slope to Graph a Line

First, find the slope of .

Slope formula

Graph the line that contains Q(5, 1) and is parallel to MN with M(–2, 4) and N(2, 1).

Graph the line that contains R(2, –1) and is parallelto OP with O(1, 6) and P(–3, 1).