Difference between revisions of "Range"

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Thus, if we have <math>f: \mathbb{R} \to \mathbb{R}</math> given by <math>f(x) = x^2</math>, the range of <math>f</math> is the set of [[nonnegative]] [[real number]]s.
 
Thus, if we have <math>f: \mathbb{R} \to \mathbb{R}</math> given by <math>f(x) = x^2</math>, the range of <math>f</math> is the set of [[nonnegative]] [[real number]]s.
 
  
 
A function is a [[surjection]] exactly when the range is equal to the codomain.
 
A function is a [[surjection]] exactly when the range is equal to the codomain.
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== See also ==
 
== See also ==
 
* [[Set notation]]
 
* [[Set notation]]
* [[AoPSWiki:Table of Contents|Table of Contents]]
 
  
 
[[Category:Definition]]
 
[[Category:Definition]]

Revision as of 22:02, 20 April 2008

Let $A$ and $B$ be any sets and let $f:A\to B$ be any function between them, so that $A$ is the domain of $f$ and $B$ is the codomain. Then $\{b\in B\mid \mathrm{there\ is\ some\ } a\in A\mathrm{\ such\ that\ } f(a)=b\}$ is called the range or image of $f$.

Thus, if we have $f: \mathbb{R} \to \mathbb{R}$ given by $f(x) = x^2$, the range of $f$ is the set of nonnegative real numbers.

A function is a surjection exactly when the range is equal to the codomain.

See also