Find the volume

Question

Find the volume of the solid obtained by rotating the region enclosed by y = x³, y = 16x , x ≥ 0 about the line y = 0 using the method of disks or washers.

Answer 1

v = π∫₀⁴(256x² - x⁶)dx = π(256x³/3 - x⁷/7)₀⁴ = π·64(256/3 - 256/7) = 65536π/21