on the graph of a function 
for which 
for all points 
close to 
At such a point, 
and is said to be stationary.
is: a point on the graph of a function for which for all points close to At such a point, and is said to be stationary.
always exists: if 
and 
This is a sufficient condition. [M4.4, P6.2]
See stationary points and graph sketching in the Maths handbook.
Copyright 1997, The Open University