Y-Axis - GCSE Maths Definition

The vertical axis on a graph is usually the y-axis. It is used to represent the dependent variable (y) in the equation of the graph. The origin on a graph will be where y = 0 (and x = 0). Depending on exactly what is being shown by the graph, y may take negative values which would be below the origin, positive numbers would above it. Together with an x-axis, the y-axis allows us to identify points in two-dimensional space. By adding a third, z-axis, we can identify points in three-dimensional space.

In GCSE Mathematics, identifying the y-axis, values on it, and their meaning, can help to quickly interpret statistical graphs or identify values for y for which a function has specific properties; for example, its gradient.