What Is Slope?
Slope measures the steepness and direction of a line. It tells you how much the y-value changes for every 1-unit increase in x. Slope is calculated as:
m = rise / run = (y₂ − y₁) / (x₂ − x₁)
A positive slope goes up from left to right. A negative slope goes down. A zero slope is a flat horizontal line. An undefined slope is a vertical line (division by zero).
Slope-Intercept Form: y = mx + b
Every non-vertical line can be written as y = mx + b where:
- m is the slope (rise over run)
- b is the y-intercept — where the line crosses the y-axis
Example: y = 2x + 3 has slope 2 (up 2 for every 1 right) and crosses the y-axis at (0, 3).