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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 Negative

If 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:



Interactive Test
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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.



Note

The Origin

The 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.