1) (n^2-n-1)(n^2-n+1) = n^4 - 2n^3 - n^2 + 2n + 1
2) 3a + 3a^2 - b - ab = 3a^2 + 3a - ab - b= 3a(a + 1) - b(a + 1)= (3a - b)(a + 1)
1) (n^2-n-1)(n^2-n+1) = n^4 - 2n^3 - n^2 + 2n + 1
2) 3a + 3a^2 - b - ab = 3a^2 + 3a - ab - b
= 3a(a + 1) - b(a + 1)
= (3a - b)(a + 1)