Calculus 10th Edition

$\frac{2\pi}{3}$
Setup the integration using disk method about the x-axis $\pi \int_1^3(\frac{1}{x})^2dx$ $\pi \int_1^3 (\frac{1}{x^2})dx$ $\pi[-\frac{1}{x}]_1^3$ $\pi(-\frac{1}{3}+1)$ $\frac{2\pi}{3}$