This is an old revision of this page, as edited by Robbot (talk | contribs) at 16:20, 22 March 2004 (Andre Engels - Robot-assisted disambiguation: Function). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.
Revision as of 16:20, 22 March 2004 by Robbot (talk | contribs) (Andre Engels - Robot-assisted disambiguation: Function)(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff)An inverse image in mathematics is defined in the following way:
Consider a function f which maps from some set A to some set B. Let C be a subset of B, then the inverse image of C under the function f, written f(C), is defined as the set of all elements in A which map into C.
Example:
Take as sets A and B the natural numbers 1, 2, 3,... Take as function f the quadratic function that assigns to every number its square. Take as subset C of B all natural numbers less than 10. Then the inverse image of C consists of the number 1, 2 and 3, since only these number have have a square less than 10, namely 1, 4 and 9.