Find the volume

Question

Using disks or washers, find the volume of the solid obtained by rotating the region bounded by the curves y=1/x, y=0, x=1, and x=4 about the x-axis 

Answer 1

By disk method volume v = π∫₁⁴1/x²dx = - π/x₁⁴ = - π/4 + π = 3π/4