Factor completely. n 4 - 1 (n2 + 1)(n - 1) (n + 1)2(n - 1)(n + 1) (n2 + 1)(n - 1)(n + 1)

We need to use formula a² -b² = (a-b)(a+b),
and here we need to use this formula 2 times.

n⁴ -1 = (n²)² -1² =(n² -1)(n²+1) = (n² -1²)(n²+1) = (n²+1)(n-1)(n+1)