6th Grade Math Textbook, Fundamentals

Lesson 13-7 for exercise sets. &KDSWHU 

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The slope of a line may be positive, negative, zero, or undefined.

Positive Slope

The slope of this line is:

2.5

2.5 is a positive number, so this line is

said to have apositive slope.

Think

A line with a positive slope rises

from left to right.

 5

 2

 1  4

0  2

y 2 y 1

x 2 x 1

0

y

x

^1423657

1

 2

 3

1

2

3

4

5

6

 7  6  5  4  3  2  1

Zero Slope

A horizontal lineis a line whose points

all have the same y-coordinate. The line

y 3 is a horizontal line. Two points on

the line y 3 are (6, 3) and (0, 3).

 0

The slope of a horizontal line is zero.

0

 6

 3 ( 3 )

 6  0

y 2 y 1

x 2 x 1

Negative Slope

The slope of this line is:

 2

2 is a negative number, so this line is

said to have anegative slope.

 6

3

 1  5

2 (1)

Think

A line with a negative slope falls

from left to right.

y 2 y 1

x 2 x 1

0

y

x

^1423657

1

 2

 3

1

2

3

4

5

6

 7  6  5  4  3  2  1

Undefined Slope

Avertical lineis a line whose points all have

the same x-coordinate. The line x4 is a

vertical line. Two points on the line x 4

are (4, 7) and (4, 1).



The slope of a vertical line is undefined.

8

0

7 ( 1 )

4  4

y 2 y 1

x 2 x 1

Remember:

Division by 0 is

undefined.

Find the slope of the line that passes through each pair of points.
Then classify the slope aspositive,negative,zero, orundefined slope.

1.(7, 4), (2, 4) 2.(1, 3), (9, 1) 3.(5, 1), (6, 10) 4.(8, 0), (8, 9)

Tell whether the function represents a direct variation.
If the function represents a direct variation, identify the constant of variation.

5.y 2 x 6.y 3 x 2 7.y5.5x 8.y x

9.Discuss and Write Look at the graph with the positive slope at

the top of the page. Describe the change in slope if point (2, 4) is

changed to point (1, 4).

3

4