Can some explain to me how to do this up to and including the x cubed term? I can do 1/(2+x) but not sure what to do with the x on top. I tried making it two fractions but got some x^6 terms which weren't in the answer books.
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Binomial expansion of (1+x)/(2+x) watch
- Thread Starter
- 07-02-2010 15:44
- 07-02-2010 15:46
1+x = (2+x) - 1
Can you see how this helps you?
- 07-02-2010 15:52
Cant you just do (1+x)(2+x)^-1 - do the binomial expansion of the second part and then times all the terms by (1+x) or am i missing something somewhere???
- 07-02-2010 15:55
Do it as (1+x)(2+x)^-1 - when expanding you you'll get terms of higher order than what you expanded (2+x)^-1 to, ignore these.
- 07-02-2010 16:18
= (1+x)2^-1(1+ x/2)^-1
=0.5(1+x)[ 1 + (-1)(x/2) + ((-1)(-2)/2!)(x/2)^2 +....]
= (0.5 + x/2) [ 1 - 0.5x + 0.25x^2 +...]
= do the rest yourself