123
L15
§3
.2
Func
t
ion
s
Definition
.
A
function
is a relation such that for each
element in the domain there is only one element in the
range.
Function Notation:
( )
yf
x
=
.
If
x
is an element in the domain of
f
, then
()
x
=
is
the corresponding element in the range.
Thus, for a function,
ab
f
a
f b
=⇒
=
,
that is, no two ordered pairs have the same first
coordinate
.
Which of the following are functions?
(
)
(
)
{ }
1,1 , 2, 2 , 3, 3 ,.
..
f
=
(
)
(
)
{ }
5,5 , 2, 3 , 5, 5 ,.
g
=−
−
(
)
( )
{ }
1,1 , 4,6 , 6,4 , 1, 2 ,.
..
h
{
(, )
}
kx
yy
x
==