f:$($R$\backslash$times R$)->($R$\backslash$times R$)$ defined by

$$

$($

$$

$,$

$$

$)$

$=$

$($

$$

$+$

$2$

$$

$,$

$$

$$

$$

$)$

f$($x$,$y$)=($x$+2$y$,$x$$y$)$