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agentx5

Is this correct? (+1 medal will be given) Q: Use the method of cylindrical shells to find the volume of the solid obtained by rotating the region bounded by the given curves about the x-axis. (x - 3) = (y − 7)\(^2\), x = 19 A: \(y = 7\pm \sqrt{(19)-3} = 3 or 11 \), therefore: \[\huge\int\limits_3^{11} (2 \pi)(y)(3 + (y − 7)^2) dy = \frac{2800 \pi}{3} \] Graph below:

  • one year ago
  • one year ago

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  1. agentx5
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    • one year ago
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  2. agentx5
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    I'm doing something wrong here I believe, because the computer is going NO! *slap*

    • one year ago
  3. dpaInc
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    i don't see anything wrong...

    • one year ago
  4. dpaInc
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    that is correct...

    • one year ago
  5. agentx5
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    Hmm, it's not taking the answer though. (online homework thing, and I thought I had this section well understood)

    • one year ago
  6. agentx5
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    Integration checks out, is it a setup error?

    • one year ago
  7. agentx5
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    Using the disk method is a non-option here I believe

    • one year ago
  8. dpaInc
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    did you enter the decimal answer instead of the exact answer? it is possible to do this using the disk (washer method) but not recommended... either way, the answer should still be the same..

    • one year ago
  9. agentx5
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    WebAssign (that's the the software provider is) allows for exact answer input (copy & paste disabled logically, but I can put it in as displayed above).

    • one year ago
  10. agentx5
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    I've double checked it and I've x = 3 + (y − 7)^2 and the rest of the instructions I've typed them over word for word. I don't see any errors in my scratch work either

    • one year ago
  11. dpaInc
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    all i can say is that there is nothing with your set-up or your integral...

    • one year ago
  12. agentx5
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    This is even one of those where you get to select the graph from multiple choice for points, and that's ok too. So what the heck WebAssign? :D

    • one year ago
  13. dpaInc
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    write to them saying you got the answer correct but the computer won't accept it AND ask for monetary compensation since it's their fault and not yours...:)

    • one year ago
  14. Eyad
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    Correct ,give me my medal ... JK,give it to Dpalnc

    • one year ago
  15. agentx5
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    HAHA!

    • one year ago
  16. agentx5
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    Maybe you all are right. I mean integration isn't that hard on this problem, and even Wolf agrees so what the heck? I tried entering it as a decimal and it slapped me down again.

    • one year ago
  17. agentx5
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    There's not some weirdness with a discontinuity of some kind here is there? I'm giving you a cookie for your hard effort @dpalnc :D

    • one year ago
  18. KingGeorge
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    Sorry I've just been sitting here so long, but don't you need to include the \(x=19\) in the part you're integrating as well?

    • one year ago
  19. KingGeorge
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    I believe you should instead be integrating \[\huge\int\limits_3^{11} (2 \pi)(y)(19-(3 + (y − 7)^2)) dy \]

    • one year ago
  20. agentx5
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    Hmm, let me try that and see... :-)

    • one year ago
  21. agentx5
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    YOU DID IT! :D Way to go @KingGeorge !!! (darn I gave out the medal earlier, I'd have given you 5 right now if I could) Hmm, now let me see if I understand why... Area between curves? y=19 is the upper layer?

    • one year ago
  22. agentx5
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    Kind of odd how it's all turned sideways because of the switch between what is normally independent and dependent

    • one year ago
  23. agentx5
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    A(y) \(\rightarrow\) Right - Left?

    • one year ago
  24. agentx5
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    @dpaInc @Eyad , he got it, FYI :-D

    • one year ago
  25. KingGeorge
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    It should be the right minus the left in your integrand for the shell method.

    • one year ago
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