# volumes of revolution ...help!!

Discussion in 'Homework Help' started by oussama123443, Nov 27, 2015.

1. ### oussama123443 Thread Starter New Member

Nov 2, 2014
27
0
hey guys...!! what is the volume of the solid when rotating the areas between y=(x^3)-x and the x-axis around the line x=1 ???

2. ### djsfantasi AAC Fanatic!

Apr 11, 2010
3,386
1,172
Hey Oussama,
Does the solid extend into infinity? At what points along $y=x^3-x$ and $x=0$ (if at all) does the solid end?

oussama123443 likes this.
3. ### oussama123443 Thread Starter New Member

Nov 2, 2014
27
0
no boundaries were given for the integral , the function has x=1 and x=-1 as roots so i'm trying to figure if the shape generated will be from " -1 to 1"

4. ### WBahn Moderator

Mar 31, 2012
19,153
5,177
The bounds are definitely important and they are not at all obvious.

What about the root at x=0?

I would recommend giving your answer in three parts. First, figure out the solid of revolution between each adjacent pairs of roots and then also give the sum of them. In addition, provide an explanation why you are using those limits as opposed to something even broader.

5. ### WBahn Moderator

Mar 31, 2012
19,153
5,177
MOD NOTE: Moved to Homework Help from Math.