The domain for any function is the set of all input values to which the rule applies. These are called the independent variables. The range is the set of all output values. These are called the dependent variables. The domain and range can be expressed as a list of numbers, in words, or using set notation.

The domain of a quadratic function f(x) is all real numbers, unless the quadratic is modeling a situation in which there is a restriction on the input values. The range is restricted by the y -coordinate of the vertex. When the vertex is a minimum, the range will be greater than or equal to its y -coordinate and when the vertex is a maximum, the range is less than or equal to its y -coordinate.