a one-to-one function, has a one to one relation obviously, meaning for every x-coordinate, there's a unique y-coordinate value, so the pairs never really repeat, let's check this one,
[tex]\bf \{(-1,\stackrel{y-re peat}{1}),(-3,-2),(0,\stackrel{y-re peat}{1}),(4,2)\}\impliedby
\begin{array}{llll}
\textit{therefore is not a}\\
\textit{ \underline{one-to-one}}
\end{array}[/tex]
