1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Integration by parts?

  1. Jan 15, 2006 #1
    integration by parts??

    just trying to figure out this integral int(x^2 (1+x^3)^4 dx)

    when i integrate by substitution i get anti deriv.... 1/15 (1+x^3)^5

    which is not the same (but close when u plug in values of x) to

    1/15*x^15 +1/3*x^12 + 2/3*x^9 + 2/3*x^6 + 1/3*x^3

    am i going about this wrong?....i'm letting u = 1 + x^3...what
     
  2. jcsd
  3. Jan 15, 2006 #2

    Tom Mattson

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Your answer is right. You must have made a mistake when plugging in values of x.
     
  4. Jan 15, 2006 #3
    bleh, mistake.
     
  5. Jan 15, 2006 #4
    1/15*x^15 +1/3*x^12 + 2/3*x^9 + 2/3*x^6 + 1/3*x^3 is the value i got from maple



    1/15 (1+x^3)^5 is the value i got by hand....


    plug in values of x....u get different results...

    if x=1...

    the first one u get 31/15...the second is 32/15
     
  6. Jan 15, 2006 #5

    HallsofIvy

    User Avatar
    Staff Emeritus
    Science Advisor

    (1/15)(1+ x^3)^5= (1/15)x^15+ (1/3)x^12+ (2/3)x^9+ (2/3)x^6+ (1/3)x^3+ 1/15.

    Do the words "constant of integration" mean anything to you?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Integration by parts?
  1. Integration by parts (Replies: 6)

  2. Integration by parts (Replies: 8)

  3. Integration by Parts (Replies: 8)

Loading...