Integration problem

  • Thread starter fran1942
  • Start date
  • #1
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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
 

Answers and Replies

  • #2
tiny-tim
Science Advisor
Homework Helper
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hello fran1942! :smile:

(try using the X2 button just above the Reply box :wink:)
x(u)^4 / 4

no, you must substitute every x …

you can't end up with something that still has an x in it!:wink:
 
  • #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.
 
  • #4
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Don't forget the constant of integration!
 
  • #5
we cannot seem to integrate plancks law to show that stefans boltzman constant is 5.67x10^-8
 

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