Show that the Modulus Function f : R → R, given by f (x) = | x|, is neither one-
one nor onto, where | x | is x, if x is positive or 0 and |x | is – x, if x is negative 5 Show that the Signum Function f : R → R, given by
f x
x
x
x
( )
,
,
� ,
=
>
=
<



1
0
0
0
1
0
if
if
if
is neither one-one nor onto 6