Mapping/Image/Definition

Image

Let ${}L$ and ${}M$ denote sets and let

$F\colon L\longrightarrow M$

be a mapping. Then the set

${}B={\left\{y\in M\mid {\text{there exists some }}x\in L{\text{ such that }}F(x)=y\right\}}\,$

is called the image of the mapping.