formula, anyone? (volume of a solid of revolution)

[tutorgirl]

Find the volume of the solid of revolution formed by rotating about the x-axis the region bounded by the curves.

y = x + 3, y = 0, x = -3, x = 7

When I did the formula from the text book I got 100n. I am not sure if this is right.

Does anyone have a formula that would help me?

 

[daon]

Re: formula, anyone?

Find the volume of the solid of revolution formed by rotating about the x-axis the region bounded by the curves.

y = x + 3, y = 0, x = -3, x = 7

When I did the formula from the text book I got 100n. I am not sure if this is right.

Does anyone have a formula that would help me?

...And how in the world did you get an n in your answer?

Remember Volume of a solid (using thing cylinders as approximations) is V = \(\displaystyle \pi r^2 h\)

r = distance from axis to the function. r = (x-3) - 0 = x-3
h = dx since you are adding many small cylinders together.

V = \(\displaystyle \L \int _{-3}^7 \pi (x+3)^2 dx\)

 

[happy]

Don't fall for the trap. This person is part of a "group" of individuals who always give any answer they can think of hoping that they will receive the correct answer.

 

[tutorgirl]

Thank you very much I am not part of any group of people. I don't know whom or what you are referring to. I just came on here to get some math advise.

Anyways,

I have a calc worksheet I am working on. And all of the possblie answers for this problem have an n in it. That also confused me so I knew I was doing something wrong.

 

[daon]

Oh well... I think Ted should implement email confirmation, IP validation and only one email address per user. Guest posters should only be able to create one thread per day via IP address... (if it isn't too much.) Just my opinion...

 

[stapel]

Thank you very much I am not part of any group of people.

There is, unfortunately, a "group" that posts very similar exercises with very similar formatting at all the same time from all the same IP, whilst claiming to be different people from different towns at different schools in different states. The member(s) of this group rarely shows any work, and often plays "multiple guess" until given the answers. This group of usernames consists currently of the following:

rachael724, rachaelmaria7, kimmy4110, kimrking101, mathman1, mathmom00, Ilovemymom, luvmykids911, iamtoostinky, MissPiggy, bigbird, TinyTim, Jeffy, Mikey, douchey, twinke, wildbill, tacobellYUM, pepepeteskitchen, josh123, thetomps, adam40g, maggie0160, ryansmith069, thegersters, AmandaLynn04, maxboy0801, isabelle2hot, TexaSASS, achillesg22, petebob6,daleross9, TYSONG, SMITH4, megynbrown1, jaredroy23, BrookeD, Dennis9, baseballpro040, complicated, OTHfan, justjenn, comeoneileen0405, bethanyj, Nathan23, JackSparrow

I apologize if you were erroneously assumed to be part of the above group.

A good way to distinguish yourself from this group would be to show your work and reasoning.

Thank you for your understanding.

Eliz.

 

[galactus]

Here's the shell method if you're interested.

\(\displaystyle \L\\2{\pi}\int_{0}^{10}y(10-y)dy\)