How do I solve [math]\lim_{x\rightarrow 0}\left | \frac{x+1}{x-1} \right |[/math] How do I solve [math]\lim\limits_{n\to\infty}\left(\frac{x}{1-x^2}+\frac{x^2}{1-x^4}+...+\frac{x^{2^n}}{1-x^{2^{n+1}}}\right)[/math] where [math]0<x<1[/math]?