Question

HAVING TROUBLE UNDERSTANDING DEFINITION OF VOLUME:
Let S be a solid that lies between x = a and x = b. If the cross-sectional area of S is the plane Px, through x and perpendicular to the x-axis, is A(x), where A is a continuous function, then the volume of S is:

V = limit of the sum i =1 to n of A(xi)*delta x

= the definite integral of A(x) from a to b