A point x = c in the domain of the function 'f' is said to be a critical point of the function 'f '
if either f '(c) = 0 or f '(c) does not exist.
The critical point x = c of a function 'f' separates the increasing and decreasing points of the function if
f ''(c) ≠ 0
Refer example 1.
A point x = c in the domain of the function is said to be a stationary point of y = f(x)
if f '(c) = 0
Refer example 2.