Hello, turtle!

Use the cylindrical shell method to find the volume of the solid generated

by revolving the region bounded by the curves about the y-axis:

. . . y = sqrt{x}, y = 0, x = 4

By using: r = 4 - x, you revolved it about the line x = 4.

It should be: . V .= .2π ∫ x·sqrt{x} dx .= .2π ∫ x^{3/2} dx