Module 6 : Definition of Integral
Lecture 16 : Integral from upper and lower sums [Section 16.1]
  is called the length of the subinterval .
(iv)
For a partition , the number
 

                   

is called the norm of the partition .

Assumptions:
In order to define the area bounded by the graph of a function , the and the lines , we assume that is a continuous function. As a consequence of this property not only is bounded on every closed subinterval of in fact it attains its bounds in that interval.

16.1.2 Definition:
 

Let be a continuous function and let
               
be a partition of .        


(i)
 Let
 
4