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 Help

  1. Aug 30, 2007 #1
    1. The problem statement, all variables and given/known data
    [tex]\int\frac{x^3 dx}{(x+1)^8}[/tex]


    2. Relevant equations
    None I can think of.


    3. The attempt at a solution
    Hm..I just don't know where to start.

    No substitution seems to be useful. (u=x+1, u=(x+1)^8).
    I've tried pulling x out of the denominator to get:
    [tex]\int\frac{x^3 dx}{x^8 (1+x^-1)^8}[/tex]
    but that doesn't help either..

    This isn't really HW just one of 15 integrals I was given that I should be able to do...

    Thanks in Advance for any hints on solving this.
     
  2. jcsd
  3. Aug 30, 2007 #2
    Cal 2? b/c i can't even go at it, i've only completed Cal 1.
     
  4. Aug 30, 2007 #3
    Yep, Calc 2.

    I "think" I could do partial fractions but...8 variables to find? and then 8 integrals of increasing power on the denominator. I think there should be an easier way...
     
  5. Aug 30, 2007 #4
    man i can't wait to be able to solve these types of problems :-]

    i've missed it so much that i even did the even problems that weren't assigned for hw
     
  6. Aug 30, 2007 #5

    Dick

    User Avatar
    Science Advisor
    Homework Helper

    u=x+1 is fine. Turns it into (u-1)^3/u^8. Now you just have to expand (u-1)^3. And if that's the worst of your 15 problems, feel blessed. It's really a calc 1 problem.
     
    Last edited: Aug 30, 2007
  7. Aug 30, 2007 #6
    Wow thanks, this is about the 2nd time I've ever seen that type of substitution being used >.<.

    Yea the problem's weren't really hard Calc 2 stuff mainly things we should know off the top of our heads.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Integration Help
  1. Integral help (Replies: 4)

  2. Integration Help (Replies: 5)

  3. Integration help! (Replies: 3)

  4. Help with an integral (Replies: 1)

  5. Integrals help (Replies: 7)

Loading...