Use the washer method to find the volume of hte solid generated by revolving the regions bounded by y= root(x) and the lines y =2 and x=0 about the x-axis , y-axis , y= 2 and x=4
V= Pi integral (0,4) (R(x)^2 - r(x)^2) dx
The Attempt at a Solution
I tried to use the equation above but I totally got confused about r(x)^2 as from what I know that the washer method means you have a small radius that you will subtract from the large curve which is in this case root(x) but there is none!
Thank you very much for your time, I would appropriate if you could explain how you solve this question so I could learn