Quantcast

A community for students. Sign up today!

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

Dido525

  • one year ago

Set up an intergal for the colume of the solid obtained by ratating the region bounded by the parabolas x=8y-2y^2, x= 4y-y^2 about the x-axis.

  • This Question is Closed
  1. Dido525
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I have no idea how to do this :( .

  2. tkhunny
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 3

    The maximum x-value for each is at y = 2. The intersections of the two are at (0,0) and (0,4). Would you like to chop it up into 3 pieces or simply apply Pappus' Theorem?

  3. Dido525
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I can't use Pappus' theorem.

  4. tkhunny
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 3

    Why not? Specifically proscribed? Not yet presented? Or just not able?

  5. Dido525
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    We won't learn it.

  6. soty2013
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    @saifoo.khan

  7. Dido525
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    First of all, I need to sketch this thing. I can't figure out how the thing looks like.

  8. tkhunny
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 3

    Think it up yourself and surprise everyone! 3 pieces then. 1) Biggest Piece x from 4 to 8 and y from \(2 - \sqrt{\dfrac{8-x}{2}}\) to \(2 + \sqrt{\dfrac{8-x}{2}}\) 2) Top Piece x from 0 to 4 and y from \(2 + \sqrt{4-x}\) to \(2 + \sqrt{\dfrac{8-x}{2}}\) 3) Bottom Piece x from 0 to 4 and y from \(2 - \sqrt{\dfrac{8-x}{2}}\) to \(2 + \sqrt{4-x}\) Go!

  9. tkhunny
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 3

    Why not flip it around to where you are more familiar and solve that problem. y = 8x-2x^2 and y= 4x-x^2 and wrap it around the y-axis!

  10. Dido525
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    But that changes the entire question.

  11. tkhunny
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 3

    No. The question is to calculate the volume. Unique answers do not care how you find them. It MUST be considered a valid methodology.

  12. tkhunny
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 3

    Anyway, you can flip it around just to get a look at it, if you can't relate to the present condition.

  13. Dido525
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    But if you switch the x and y's that should change the entire shape of the graph.

  14. tkhunny
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 3

    That's silly. Why would you think that? Absolutely not the case. It is the EXACT SAME problem.

  15. Dido525
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    |dw:1359609779642:dw| Something like that? REALLY bad sketch though.

  16. tkhunny
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 3

    |dw:1359609887178:dw| A little better. You crossed the x-axis. That's no good.

  17. Dido525
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    yeah I know. I felt lazy.

  18. tkhunny
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 3

    Well, go ahead and do it, then. I gave you all the limits up above. Good luck. gtg

  19. Dido525
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Thanks!

  20. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Ask a Question
Find more explanations on OpenStudy

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.