I assume you derive it: 1/(1+(x/3)²)
then put it in the proper formation: 1/(1- (-x/3)²)
so then I get the sigma of -1^2n -x/3²^n
and then I have to take the integral?
I just don't get what to do, like the proper formation. Why do I have to keep the -1 and -x/3 seperate if they are both to the 2n power?
And in an unrelated note, when do you have to change the index? I don't get that AT ALL.