Definition: The area of the region
that lies under the graph of
the continuous function is the limit
of the sum of the areas of approximating
rectangles
(a) Use the above definition to determine which
of the following expressions represents the area
under the graph of from
to .
A. B. C. D.

(b) Evaluate the limit that is the correct answer
to part (a). You may find the following formula
for the sum of cubes helpful: