Question

can someone please help with the disk and washer method? PLEASE!!!!!

Answer 1

Find the volume of the solid generated by the region bounded by the graphs of th following lines revolved around the line x=5:
xy=5
y=2
y=5
x=5

Answer 2

I understand that I have to find the volume of both regions and subtract the volume not needed from the volume needed in order to get my solution. I am just having a hard time figuring out how to do this. I am aware that you have to integrate it with respect to either x or y based on what axis it is revolved around. Then the formula is \[\pi \int\limits_{x=a}^{x=b}(R(x))^2-(r(x))^2dx\] my problem is when you get an axis that is not the x axis or the y axis I get confused as to how to represtent R(x) and r(x). I understand that solids of revolution being revolved around a vertical axis have to be integrated with respect to Y (dy) and solids revolved around horizontal axis must be integrated with respect to x (dx). I just don't understand how to to represent the functions when they are not on the x or y axis

Answer 3

I'm not a big fan of the dish washer method

Answer 4

nor am I but is a necessary evil :)

Answer 5

I was joking subtly. I referred to the disk and washer method as the dish washer method.

Answer 6

so can you help? I just need to find how to express these values of big R (as my professor calls it) and little r

Answer 7

I could if I wasn't so busy

Answer 8

thanks

Answer 9

Maybe one of these guys can help:

@myininaya
@dumbcow
@TuringTest
@satellite73
@amistre64
@Omniscience

Answer 10

@across

Answer 11

here is what i come up with

R = 5-(5/y)
\[V = \pi \int\limits_{2}^{5}(5-\frac{5}{y})^{2} dy\]