Which of these functions has a Maclaurin series ∑n=0∞x2n+1\sum_{n=0}^{\infty} x^{2n+1}∑n=0∞x2n+1?
x1−x2\frac{x}{1-x^2}1−x2x
11−x\frac{1}{1-x}1−x1
x1+x2\frac{x}{1+x^2}1+x2x
x21−x\frac{x^2}{1-x}1−xx2