Barrons AP Calculus - David Bock

34. (B)

Use disks; then ΔV = πR^2 H = π(ln y)^2 Δy. Note that the limits of the definite integral are 1

and 2. Evaluate the integral

Alternatively, use shells*; then ΔV = 2πRHT = 2πx(2 − ex) Δx. Here, the upper limit of

integration is the value of x for which ex = 2, namely, ln 2. Now evaluate

* No question requiring the use of the shells method will appear on the AP exam.