1. Limited time only! Sign up for a free 30min personal 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!

Homework Help: Binomial expansion

  1. Jun 24, 2008 #1
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Jun 24, 2008 #2

    rock.freak667

    User Avatar
    Homework Helper

    For [itex](a+b)^n[/itex] where n is fractional or negative, is valid for |b/a|<1.


    For the question, 'b' in this case is x/(1+x) and 'a' is 1

    so | x/(x+1) |<1

    But you must also remember that |X|<1 means -1<X<1 i.e. X<1 and X>-1

    so for the question you'd need to take each case of x/(x+1) <1 and find where that is valid for and find where x/(x+1)>-1 and find the "intersection" of both those sets of values if you understand what I am saying.
     
  4. Jun 25, 2008 #3
    Hi Thanks alot for the help. The final answer is (1 + x)^2, therefore should it not just be l X l <1? Why is it l (x/(1+x)) l < 1 , which is an intermediate step.

    Thanks
     
  5. Jun 25, 2008 #4

    rock.freak667

    User Avatar
    Homework Helper

    As I said before

    For [itex](a+b)^n[/itex] where n is fractional or negative, is valid for |b/a|<1.


    For the question, 'b' in this case is x/(1+x) and 'a' is 1

    so | x/(x+1) |<1


    and this means that

    [tex] -1< \frac{x}{x+1}<1[/tex]
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook




Loading...
Similar Threads for Binomial expansion Date
Binomial Expansion (Arfken/Weber/Harris 1.3.9) Jan 5, 2018
Binomial Expansion Problem Sep 10, 2017
Binomial expansion for fractional power Mar 23, 2016
Binomial Expansions. Feb 9, 2016
DiffEq, Binomial Expansion and limits Feb 8, 2016