Functions and graphs > Domain and range
12345Domain and range


The set of all input values that are allowed are called the domain of the function. The domain is defined by

  • restrictions due to the function rule;

  • restrictions due to the situation.

The domain of a function f is written as D f .

The set of all possible function values is called the range of the function. In order to determine the range of a function f you need a complete graph of f . It is important that the vertices of the graph are visible. At a vertex, the function has a (local) maximum (largest function value) or a (local) minimum (smallest function value). The range of a function f is written as B f .

You often use interval notation to show the domain and range of a function.
An interval is a continuous set of real numbers, a stretch of the number line. The set of real numbers is written as .

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