and this will be the whole area from up to any value of that we may assign.
Therefore, the larger area up to the superior limit will be
;
and the smaller area up to the inferior limit will be
.
Now, subtract the smaller from the larger, and we get for the area the value,
.
This is the answer we wanted. Let us give some numerical values. Suppose , , and and . Then the area is equal to
Let us here put down a symbolic way of stating what we have ascertained about limits:
,
where is the integrated value of corresponding to , and that corresponding to .