Definition
1. We say that f(x) consist an absolute (or global) maximum at x = c if f ( x ) ≤ f (c ) for every x in the domain we are working on.
2. We say that at x = c , f(x) consist a relative (or local) maximum if f ( x ) ≤ f (c ) for every x in some open interval approximately x = c .
3. We say that f(x) consist an absolute (or global) minimum at x = c if f (x) ≥ f (c) for every x in the domain we are working on.
4. We say that f(x) consists a relative (or local) minimum at x = c if f ( x ) ≥ f (c ) for every x in some open interval approximately x = c .