Simplify: 1x−11x+1\frac{\frac{1}{x-1}}{\frac{1}{x+1}}x+11x−11
x+1x + 1x+1
x−1x - 1x−1
x+1x−1\frac{x+1}{x-1}x−1x+1
x−1x+1\frac{x-1}{x+1}x+1x−1