Simplify: x4−1x2−1\frac{x^4 - 1}{x^2 - 1}x2−1x4−1
x2+1x^2 + 1x2+1
x2−1x^2 - 1x2−1
x2−11\frac{x^2-1}{1}1x2−1
x−1x - 1x−1