Select the function that does not have a well$-$defined inverse.

$f$:RlongrightarrowR

$f(x)=3x+4$

$f$:RlongrightarrowR

$f(x)=-2x+5$

$f$:RlongrightarrowZ

$f(x)=|$~$x$~$|$

$f$:ZlongrightarrowZ

$f(x)=|$~$x+2$~$|$