Mapping/Image/Definition

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

${\displaystyle F\colon L\longrightarrow M}$

be a mapping. Then the set

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

is called the image of the mapping.