# Thread: [SOLVED] volume by cylindrical shell

1. ## [SOLVED] volume by cylindrical shell

I originally posted this in Calculus section and I don't know how to delete it. Can someone do that for me please? I'm getting close to my deadline, so I really need someone to check that I have my integral set up correctly. I can not get the right answer

Bounding curves:

$\displaystyle y = 8 - x^2$ and $\displaystyle y = x^2$

Find volume of region bounded by these curves when rotated about x = 2

I wrote my integral as:

$\displaystyle \int\limits_{-2}^{2} (2-x)((8-x^2)-(x^2)) dx$

Look okay?

2. Hello, mollymcf2009!

Bounding curves: .$\displaystyle y \:= \:8 - x^2 \,\text{ and }\,y \:=\: x^2$
Find volume of region bounded by these curves when rotated about $\displaystyle x = 2.$

I wrote my integral as: .$\displaystyle \int_{-2}^2 (2-x)\left[(8-x^2)- x^2\right]\,dx$

Look okay?

Probably an oversight, but you need $\displaystyle {\color{red}2\pi}$ in front . . . The rest is fine!

3. Thank you so much!! Yes, I usually just move the $\displaystyle 2\pi$ out immediately so I forgot to add that.
Thanks again!!

4. Originally Posted by mollymcf2009
I originally posted this in Calculus section and I don't know how to delete it. Can someone do that for me please?
Done. Next time, please do the following:

1. Repost the unwanted post using the Report Post tool found top right.
2. Edit the unwanted post to something like "Please delete, post reported".