MATHEMATICS · Subjective · AP · Calculus AB · Applications of Integration · Applications of Integration
Problem
In one or two sentences, explain why, when a planar region bounded by two non-negative functions y=f(x) (outer) and y=g(x) (inner) is revolved about the x-axis, the integrand for the volume involves f(x)2−g(x)2 rather than f(x)−g(x).