*Macmillan Science Library: Mathematics*. Copyright © 2001-2006 by Macmillan Reference USA, an imprint of the Gale Group. All rights reserved.

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## Examples of Functions

A simple example of a function is *y* = *f*(*x*), where *f*(*x*) = *x* + 2. To each number *x,* add 2 to get *y.* When *x* is 3, *y* is 5, and when *x* is 4, *y* is 6. The value *y* of the function, *f*(*x*)*,* depends on the choice of *x.* The input, or *x,* is called the independent variable, and the output, or *y,* is called the dependent variable.

Another example is a relationship between the positive **integer** set (domain) and the even number set (range). To each positive integer *n,* the function *f*(*n*) assigns a value of 2*n.* In symbols, *f*(*n*) = 2*n.*

In a function, each element of the domain must map to exactly one element of the range. However the opposite is not true. For example, *f*(*x*) = |*x*| is a function. Each value of *f*(*x*) corresponds to...

This section contains 504 words(approx. 2 pages at 300 words per page) |