Y-axis

Definition

The y-axis is the vertical number line in a rectangular coordinate system. It is used to represent the second coordinate in an ordered pair (x, y).

5 Must Know Facts For Your Next Test

1. The y-axis intersects the x-axis at the origin, which is the point (0, 0).
2. Positive values on the y-axis are located above the origin, while negative values are below.
3. In an ordered pair (x, y), the y-coordinate indicates how far up or down a point is from the x-axis.
4. Graphs of functions can be reflected across the y-axis to show symmetry.
5. Vertical lines run parallel to the y-axis and have equations of the form x = c where c is a constant.

Review Questions

• What is the position of a point with coordinates (0, -3) relative to the origin?
• How would you describe a function that is symmetric about the y-axis?
• What is the equation of a vertical line passing through x = -2?

Related terms

x-axis:

The horizontal number line in a rectangular coordinate system used to represent the first coordinate in an ordered pair (x, y).

Origin: The point of intersection between the x-axis and y-axis in a rectangular coordinate system, denoted as (0, 0).

Quadrants: The four regions created by dividing a plane with an x-axis and a y-axis. Each quadrant has different signs for coordinates.