Determining Series for g(x)=1/(1+7x)^2

[aces9113]

Homework Statement

Determine the series for the function g(x)=1/(1+7x)^2

Homework Equations

______∞___________________∞
1/(1-x)=∑ x^n and 1/(1-x)^2=∑nx^(n-1)
______n=0________________n=1

The Attempt at a Solution

I tried to apply those equations as best I could because for the last problem, I found that
1/(7+x)=(-1)^n*7^n*x^n but I couldn't get the right answer. Any help would be appreciated

 

[lineintegral1]

This is can be written as a binomial series. Take a look at your formulae for that. If you are not familiar with these, let us know.

 

[aces9113]

we've never gone over anything called binomial series. please elaborate or simplify!

 

[aces9113]

could someone please explain how to do this the binomial series way, I've never learned it

 

[Unit]

You can start with $(1-x)^{-1}$, differentiate once, and make an appropriate substitution (i.e. y = -7x).