# Find the volume of the solid obtained by rotating the region enclosed by

• December 4th 2008, 10:46 AM
derrickd
Find the volume of the solid obtained by rotating the region enclosed by
Find the volume of the solid obtained by rotating the region enclosed by
y = (x^2) − 1, y = 2x − 1 about y = 4 .
• December 4th 2008, 02:21 PM
derrickd
bump
• December 4th 2008, 03:30 PM
skeeter
find the imits of integration ...

$x^2-1 = 2x-1$

$x^2 - 2x = 0$

$x(x-2) = 0$

$x = 0$ ... $x = 2$

using the method of washers ...

$R(x) = 4 - (x^2-1)$

$r(x) = 4 - (2x-1)$

$V = \pi \int_0^2 [R(x)]^2 - [r(x)]^2 \, dx$