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Area of a straight line the claculus way,

  1. May 15, 2006 #1
    area under a straight line the calculus way,

    the book gets by means of the regular definit integral method as oppossed to the fundamtenal theorem of calculus method,

    S of n = 2deltaX+2deltaX+2(deltaX)^2+2deltaX+2x2(deltaX)^2+ . . . +2deltaX+2(n-1)(deltaX)^2

    from the general terms arrived at prior.

    The book then notes there are 2deltaX's in each term, and there are 2n deltaX's.

    But then, it factors out, not 2deltaX's, but 2(deltaX)^2, and that becomes times the progression [1+2 . . . + (n-1)]

    As indicated, I see where it gets the 2ndeltaX as an expression for all the 2deltaX's, but then, it just quite mysteriously to me drops it, and factors out 2(deltaX)^2's! Which I'd understand if that was the common term, but where and how did the 2ndeltaX term get taken out?
     
    Last edited: May 15, 2006
  2. jcsd
  3. May 15, 2006 #2

    Curious3141

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    This is Physicsforums.com, not PsychicForums.com. :rofl: Could you be a little less cryptic, please? :smile:
     
  4. May 15, 2006 #3
    seems the easiest things make the hard things hard; the post is clear; i can understand that maybe you don't have an answer because something is up with the problem I've found, but that doesn't mean taking on the snobishness of the anti-intellectuals!
     
  5. May 15, 2006 #4

    Curious3141

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    No snobbishness intended. Just telling you in all humility and honesty that I can't make head or tail of what you're asking about.:rolleyes:
     
  6. May 15, 2006 #5
    the only thing I can think of to improve on english has been so edited, everything else is carbon copy, so there shouldn't be any confusion unless 1) the book really is way off, or 2) you don't know how to solve the problem.
     
  7. May 15, 2006 #6

    Curious3141

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    First of all, your original post was titled "area of a straight line" which made absolutely no sense. "Calculus" was also misspelled, but that wasn't a big deal.

    Second, your current post is STILL full of obvious typos and symbolic errors, for e.g. *what* "times the progression..."??

    Third, my initial post was made in jest, hence the smilies. You obviously chose to take offence at that.

    Fourth, lose the attitude, or you're going to get very little help here. This is not a paid service, we do this out of altruism, we can just as easily choose not to help.

    This seems like a fairly trivial infinitesimal element summation. If you want people to help you make sense of the book, I suggest you scan in the relevant section so there will be absolutely no confusion. Either that, or learn to put your expressions into LaTex format, the board supports it.
     
  8. May 15, 2006 #7

    Gokul43201

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    1. State the question exactly as it appears in the book.

    2. If you are writing down some part of the working from the book, provide the info needed to understand this, including :

    (i) what the symbols mean,
    (ii) what was accomplished before arriving at the step you start from,
    (iii) any assumptions or definitions along the way.

    3. Write complete mathematical equations rather than half-equations.
     
  9. May 15, 2006 #8

    Gokul43201

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    Is this what you are saying ?

    [tex]S(n) = 2(\Delta x) + 2(\Delta x) + 2\cdot 1(\Delta x)^2 + 2(\Delta x) + 2\cdot 2(\Delta x)^2 + ... + 2(\Delta x) + 2(n-1)(\Delta x)^2 [/tex]

    [tex]= 2n(\Delta x) + 2(\Delta x)^2 [1 + 2 + ... + n-1 ] [/tex] ?

    ...but somehow, the book dropped the first term in the second line ?



    What does S(n) represent and how is it constructed ?
     
    Last edited: May 15, 2006
  10. May 15, 2006 #9
    so, factor out the deltas, set them to zero, and then I just have the progression to work with; o.k. and I'll admit, that maybe I wasn't clean enough on my own paperwork to see what to do, but the book also was not clear on this.

    As for the other isssue that cropped up on this thread, well, considering(maybe hopefully?!), you were not involved in my previous conflicts on this website, but, I've gotten nothing but attitude in my previous posts(both simplistic problems such as this and philosophical posts on some of the other messageboards on this website), and your(Curious3141 ) first reply is pretty borderline; well, I can only hope that you are sincere, but maybe your just trying to save face, so, if you really want to fix this issue, try bringing this up with the mods.

    P.S.

    I've also nothing but attitude and 'high school social gaming tricks' conditioning in the intellectuals at the local community college which I'm glad to be through with. So, if you 'really' want to get down to the bottom of this, go ahead and contact Grossmont college(Mrs Gaipa is the 'only' one I recall leaving on good terms with; and no, it's not me; i got out of the navy, and yes, I banged heads with the people and the airplane for four years; i know what attitude is! and came to Grossmont college, I was expecting to get away from such 'high schoolness gangbanging', but instead, i've delt with more you know what than even this thread can contain!)

    I am 'sooooooooooooooo!!!' amazed with the conditioning and 'immaturity mongering' amongst contemporary supposedly intellectuals!

    Jacob Bronowski? Pirsig? Who are they!?
     
  11. May 15, 2006 #10

    Gokul43201

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    I completely sympathize with Curious' reaction to your OP. It was incredibly hard to understand, and you still haven't explained the details of that calculation that we were asking for.

    Any other discussion you wish to have about the moderation on these forums is off-topic to this thread. Such complaints may be posed in a new thread in the Feedback forum or by PM with the moderator who took action.
     
    Last edited: May 15, 2006
  12. May 15, 2006 #11
    i'll post later;
     
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