Simplify: (x2+1)(x2−1)(x^2 + 1)(x^2 - 1)(x2+1)(x2−1).
x4−1x^4 - 1x4−1
x4+1x^4 + 1x4+1
x2−1x^2 - 1x2−1
x4−2x2+1x^4 - 2x^2 + 1x4−2x2+1