# Math Help - Confused of Volume of Solids(Washers Method)

1. ## Confused of Volume of Solids(Washers Method)

Find the volume of the solid formed by revolving the region bounded by the graphs of y=1-x^3, x=-2, and y=1 about the line x=-2. Correctly write the integral, use calculator to solve. Answer:10.053

So I solved the integral for dx and here is my integral.

integral from 0 to -2 of (3-x^3)^2 x pi

I keep on using the fnInt function, but I never got the answer(I've gotten 15.883)

2. using disks ...

$y = 1 - x^3$

$x^3 = 1 - y$

$x = \sqrt[3]{1-y}$

$R(y) = \sqrt[3]{1-y} - (-2) = \sqrt[3]{1-y}+2$

$V = \pi \int_1^9 (\sqrt[3]{1-y}+2)^2 \, dy = 10.053$

using cylindrical shells ...

$V = 2\pi \int_{-2}^0 (x+2)(-x^3) \, dx = 10.053$