## Key Concepts

- A function is a special relation in which each input corresponds to exactly one output. An input is called the independent value, and an output is called the dependent value.
- The set of all input values makes up the domain, and the set of all output variables makes up the range of the function.
- A function may be described using notation stating that the output
*y*is dependent upon the input*x*by writing [latex]y = f(x)[/latex]. - We may identify whether a relation represents a function from a table of values, a set of ordered pairs, or a graph.
- Functions may be evaluated for numerical or variable inputs

## Glossary

**domain**- the set of all input values into a function
**function**- a specific type of relation in which each input value corresponds to one and only one output value.
**function notation**- a notation used for representing output as a function of input, [latex]y=f(x)[/latex], that is
*y is a function of x* **range**- the set of all output values of a function
**relation**- a correspondence between sets of values or information
**vertical line test**- a method for determining graphically whether a relation represents a function