In order to tackle such problems,
we first formally define maximum or minimum values of a function, points of local
maxima and minima and test for determining such points Definition 3 Let f be a function defined on an interval I Then
(a)
 f is said to have a maximum value in I, if there exists a point c in I such that
( )
( )
f c>
f x , for all x ∈ I The number f (c) is called the maximum value of f in I and the point c is called a
point of maximum value of f in I