Volume of Revolution: y=5, y=x+4/x; x=-1

[mace2]

Homework Statement

"The region bounded by the given curves is rotated about the specified axis. Find the volume of the resulting solid by any method."

y=5, y=x+4/x; about x=-1

Homework Equations

Upon plotting it I decided it would be best to use the shell method. I'm not sure how to express it in your fancy symbols but I included all of my work as an attachment.

The Attempt at a Solution

Please see attachment. The correct answer is actually 8pi(3-ln4). I have gone over it a few times and I don't see what I did wrong. Any advice whatsoever would be great, thanks.

P.S. Sorry the image is grainy, I didn't know how to make it small enough to fit the guidelines and still be legible.

 

[mace2]

Ah I just figured it out. I accidentally wrote 5-x+4/x, when i really meant 5-(x+4/x).

Stupid parantheses!

 

[HallsofIvy]

Perhaps it's not the parentheses that are stupid!