Simplify: 1−1x1+1x\frac{1 - \frac{1}{x}}{1 + \frac{1}{x}}1+x11−x1
x−1x+1\frac{x-1}{x+1}x+1x−1
x+1x−1\frac{x+1}{x-1}x−1x+1
111
−1-1−1