Definition 1121 Let A be a set o real numbers i e A s R Then

Definition 11.2.1 Let A be a set o real numbers, i e. A s R. Then b is a mnim when element of A or t = min A (0) b is an element of A, i.e. beA, st(ii) b is less than or equal to every element of A, ie. aeA b s a

Solution

Let there be 2 elements c1 and c2 which are two maximum element of set A
then from definition of max element in definition 11.2.1

c1 is graeter than or equal to every other element of A
that is c1>= c2   ...eqn 1

also,
c2 is graeter than or equal to every other element of A
that is c2>= c1 ...eqn 2

eqn 1 and eqn 2 both can be satisfied only if c1=c2

So there is one and only one maximum element of set A