Fermat's
Theorem
If
f
is
a
function
for
which
:
f
(
x
)
is
____________________
at
x
=
c
;
f'
(
c
)
exists
(
i
.
e
.
f
is
____________________
at
c
)
.
f
(
x
)
has
a
____________________
min
or
max
at
the
point
(
c
,
f
(
c
)
)
;
Then
it
must
be
that
f'
(
c
)
=
0
.
In
other
words
,
f
has
a
____________________
____________________
at
x
=
____________________
.
