Editing Function of a real variable (section)

===Image===
{{Main|Image (mathematics)}}
The [[image (mathematics)|image]] of a function <math>f(x)</math> is the set of all values of {{mvar|''f''}} when the variable ''x'' runs in the whole domain of {{mvar|''f''}}. For a continuous (see below for a definition) real-valued function with a connected domain, the image is either an [[interval (mathematics)|interval]] or a single value. In the latter case, the function is a [[constant function]].

The [[preimage]] of a given real number ''y'' is the set of the solutions of the [[equation]] {{nowrap|1=''y'' = ''f''(''x'')}}.