展开成泰勒级数（taylor series)

题目

展开成泰勒级数（taylor series)
将1/(x^2+1)展开成泰勒级数~~
a=0

答案

1/(x+1)=1-x+x^2-x^3+x^4-x^5+.+(-1)^nx^n+...|x|