function

A function usually links two variables, such that it is possible to work out the value of one of the variables using the value of the other.

The equation y = x² + 3 is an example of a function which links the variables x and y. If we know the value of x, we can calculate the value of y.

For example, if x is 6, then:

y = 6² + 3

y = 36 + 3

y = 39