So the way I did it was since I know the graph is being rotated around the y-axis, I know that we are dealing with circles as cross sections. So now I need to know how much of each circle is contained in the region. So the region revolved to the y-axis is a quarter rotation, So the cross sections will be quarter circles. So now we have the integral from 3 to 0 of the equation 1/4pi(y^2/3)^2 dy. Put the 1/4pi on the other side for now and take the integral from 3 to 0 of y^4/9 dy, which is y^5/45 = 243/45 x 1/4pi. Since this is one eight of the total volume multiply this value by 8 to get 486pi/45. I hope this is right. Let me know if you have any questions.
May 20th, 2015
Studypool's Notebank makes it easy to buy and sell old notes, study guides, reviews, etc.