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Integration problem

  1. Feb 9, 2012 #1
    Hello, I am trying to integrate the following using "u-substitution", however I am not getting the correct result. Can someone please advise where I am going wrong.
    The following is my attempt:

    x(x-1)^3

    u = x-1

    du/dx = 1
    du/1 = dx

    x(u)^4 / 4

    My final (incorrect) answer.
    x(x-1)^4 / 4
     
  2. jcsd
  3. Feb 9, 2012 #2

    tiny-tim

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    hello fran1942! :smile:

    (try using the X2 button just above the Reply box :wink:)
    no, you must substitute every x …

    you can't end up with something that still has an x in it!:wink:
     
  4. Feb 13, 2012 #3
    You should rewrite the equation. If you foil out the (x-1)3 to x3-3x2+3x-1 then multiply by the x to get x4-3x3+3x2-x I think you will have an easier time integrating and without using a u-sub.
     
  5. Feb 13, 2012 #4
    Don't forget the constant of integration!
     
  6. Mar 20, 2012 #5
    we cannot seem to integrate plancks law to show that stefans boltzman constant is 5.67x10^-8
     
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