I've been having trouble solving this problem for a long time.
I used the variables:
a=1 , b = 2
Height = x^2
Radius : 1+ x
And took the integral of it using the cylindrical shell method.

Ive been having trouble solving this problem for a long time I used the variables a1 b 2 Height x2 Radius 1 x And took the integral of it using the cylindrical class=

Respuesta :

The radius should be  "x - 1" .

The region is revolving around the line x= 1. The radius is distance from this line.  So radius varies from 0 to 1 as x goes from 1 to 2. 
Therefore ,  r = x - 1.

Everything else is correct.

Here is the integral solution:

[tex]V = 2\pi \int_1^2 (x-1) x^2 dx \\ \\ = 2\pi \int_1^2 x^3 -x^2 dx \\ \\ = 2\pi |_1^2 (\frac{x^4}{4} - \frac{x^3}{3}) \\ \\ =2\pi (\frac{4}{3} - (-\frac{1}{12})) \\ \\ =\frac{17\pi}{6} [/tex]