Y-intercept

Definition

The y-intercept is the point where a graph intersects the y-axis. In an equation of the form $y = mx + b$, it is represented by the constant term $b$.

5 Must Know Facts For Your Next Test

1. The y-intercept occurs when $x = 0$.
2. In the equation $y = mx + b$, the y-intercept is $b$.
3. To find the y-intercept from a graph, locate where the line crosses the y-axis.
4. In a table of values, the y-intercept corresponds to the output value when the input is zero.
5. For vertical lines (undefined slope), there is no y-intercept unless it passes through the origin.

Review Questions

• What is the y-intercept in the equation $y = -2x + 5$?
• How do you determine the y-intercept from a graph?
• Why does a vertical line generally not have a y-intercept?

Related terms

Slope: The measure of steepness or incline of a line, usually denoted as $m$ in linear equations.

x-Intercept: The point where a graph intersects the x-axis; occurs when $y=0$.

Linear Equation: An equation that makes a straight line when it is graphed, commonly written in forms such as $y = mx + b$.