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Antiderivative of x(e^x)+5x

  1. Sep 18, 2006 #1
    I used to be able to do stuff like this when i was in high school but now im in college and i cant do basic stuff like this. the problem this sub problem is from is

    Find the volume of the solid formed by rotating the region enclosed by
    y=e^{ x} + 5, \ y=0, \ x=0, \ x=0.1

    Im trying to solve it with the shell method but i cant seem to get it right

    I thought should be the integral from 0 to .1 of (xe^x)+(5x) and then times 2pi for the # in front of the integral.
     
    Last edited: Sep 18, 2006
  2. jcsd
  3. Sep 18, 2006 #2

    radou

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    Try times 2*0.1*Pi in front of the integral.
     
  4. Sep 18, 2006 #3
    psh my bad the answer was .19067 and not .19037. I hate doing work online for a class where the professor wastes 40 minutes explaining the stupid theorem behind why the shell method works when she could have just put the formula up and i would have gotten it right away. Maybe im just dumb but i got a 5 on the ap calculus exam and the highest grade in the class both semesters. Why do the professors waste so much time on pointless crap?
     
  5. Sep 18, 2006 #4
    Why? (more characters)
     
  6. Sep 19, 2006 #5

    HallsofIvy

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    Yes, it's terrible when professors expect you to learn something instead of just memorizing formulas. Why that would involve thinking!
     
  7. Sep 19, 2006 #6
    Maybe, it's the fact that she has a thick accent and every seat except the front center seats can't read the majority of the stuff she writes on the board since the classroom is big and flat and not sloped as it should be for a class that size. Though I probably shouldnt complain given that this is low math compared to what I'm going to have to do later on.
     
  8. Sep 19, 2006 #7

    radou

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    I assumed rotation around the y-axis. If it's rotation around the x-axis, then [tex]\pi \int_{0}^{0.1}(e^x+5)^2dx[/tex] is used.
     
  9. Sep 19, 2006 #8

    HallsofIvy

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    Then make sure you get a set in the front center! When I was a freshman, I had a teacher who talked about "delters" and "epsilons". I couldn't complain- it was in Boston and that's their language. When I was in graduate school I had a teacher from Cuba. A friend asked if she could copy the teacher's notes (he taught from several pages of notes!) but they were all in Spanish!
     
  10. Sep 19, 2006 #9

    HallsofIvy

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    Then make sure you get a seat in the front center! When I was a freshman, I had a teacher who talked about "delters" and "epserlons". I couldn't complain- it was in Boston and that's their language. When I was in graduate school I had a teacher from Cuba. A friend asked if she could copy the teacher's notes (he taught from several pages of notes!) but they were all in Spanish!

    Now, I teach in sign language, my students are all deaf or hard of hearing and they have to put up with my "accent"!
     
    Last edited: Sep 20, 2006
  11. Sep 19, 2006 #10
    But the original post specifically said that the shell method was being used and not rotation about either axis.
     
  12. Sep 19, 2006 #11
    intergration by parts is your friend, at least for the first bit. the second bit you can, as im sure you know, do seperately

    oh and i think the previous posters are missing the x infront of the exponential, or im missing something you guys said
     
    Last edited: Sep 19, 2006
  13. Sep 20, 2006 #12

    radou

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    Sorry. Wasn't familiar with the term 'shell method'.
     
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