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 Substitution

  1. Jul 25, 2009 #1
    1. The problem statement, all variables and given/known data
    I've come across the problem
    [tex]\ \int x(x^{2}+5)^{75} dx[/tex]


    2. Relevant equations



    3. The attempt at a solution
    Once going through the whole problem I got [tex]\ \frac{(x^{2}+5)^{76}}{76}+c[/tex]
    but the text I have said the answer was, [tex]\frac{1}{152}(x^{2}+5)^{76}+c[/tex].
    What did I do wrong?
     
  2. jcsd
  3. Jul 25, 2009 #2
    Did you try differentiating the answers to see which one gives you [tex] x(x^{2}+5)^{75} [/tex] ? Remember to apply the chain rule and that differentiating [tex] x^{2}+5 [/tex] gives 2x
     
  4. Jul 26, 2009 #3

    HallsofIvy

    User Avatar
    Staff Emeritus
    Science Advisor

    Presumably you let u= x^2+ 5. Then du= 2x dx. You forgot the "2".
     
  5. Jul 26, 2009 #4
    Oh, now I see, thanks.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Integration by Substitution
  1. Integral substitution? (Replies: 3)

  2. Integral substituting (Replies: 4)

Loading...