FAQ - Terms of Use - Contact Us

Chapter 12    Graphing

12-7   Finding the Slopes of Lines

Points are important parts of a line. It takes at least two points to define a line. You have already seen how two point determine where a line is located. But there is another very important quality:  the slope of the line. The slop is like the "slant" or "steepness" of a line on the coordinate plane.

• A line with a positive slope rises from left to right.
• A line with a negative slope falls from left to right.
• A line with zero slop is a horizontal line.
• A line with an infinite (undefined) slope is a vertical line.

The change in y = y₂ – y₁

The change in x = x₂ - x₁

The

To find

The slope of a line is a number that indicates the "steepness" of the line. A straight horizontal line has no "steepness" at all. So we say that a horizontal line has a slope of 0 — it has no slope. On the other hand, a straight vertical line is infinitely steep. You can't make a line any steeper than a straight vertical, up-and-down line; so we say a vertical line has a slope of infinity (¥).

y = mx + b

Point 1 = (1,3) and Point 2 = (-3,7)

Copyright © 2006, David L. Heiserman
All Rights Reserved