X-Coordinates (Mathematics Glossary)
What Is the X-Coordinate?The x-coordinate is the first number in the pair of numbers used to describe Cartesian coordinates.
For example, in the Cartesian coordinates (2,4), the x-coordinate is 2 (the number on the left):
What Does the X-Coordinate Mean?The x-coordinate tells you how far across the horizontal x-axis a point is on a graph (measured from the origin).
If a point has Cartesian coordinates (2,4), the point would be 2 units along the x-axis. The image below shows what we mean by a point being 2 units along the x-axis (measured from the origin):
Note: The x-axis is labelled with numbers (0, 1, 2, 3...) so you can measure how far across the point is.
The X-Coordinate Can be Positive...If you go right along the x-axis (starting at the origin, where it crosses the y-axis), it is labelled with positive numbers (0, 1, 2, 3...).
The x-coordinate of any point to the right of the y-axis is positive.
Imagine a point had an x-coordinate of 4. It would be 4 units to the right of the y-axis:
...Or the X-Coordinate Can be NegativeIf you go left along the x-axis (starting at the origin, where it crosses the y-axis), it is labelled with negative numbers (0, -1, -2, -3...).
The x-coordinate of any point to the left of the y-axis is negative.
Imagine a point had an x-coordinate of -4. It would be 4 units to the left of the y-axis:
Here's a second test on the x-coordinate.
Here's a third test on the x-coordinate.
Which Axis Is Which?The x is a cross - so the x-axis goes across!
The y-axis must go up.
The OriginThe point labelled with a 0 on the x-axis is called the origin.
What Are Cartesian Coordinates?Cartesian coordinates are used to describe the position of a point on a graph.
Cartesian coordinates work by measuring how far across and how far up the point is from the origin.