1) 7a² - 7 = 7(a² - 1) = 7(a - 1)(a + 1)
2) 3b² - 3b = 3b(b - 1)
3) 2x³ - 2xy² = 2x(x² - y²) = 2x(x - y)(x + y)
4) -8a⁵ + 8a³ - 2a = -2a(4a⁴ - 4a² + 1) = -2a(2a² - 1)²
5) x - 4y + x² - 16y² = (x - 4y) + (x - 4y)(x + 4y) = (x - 4y)(x + 4y + 1)
6) ab⁶ - ab⁴ - b⁶ + b⁴ = ab⁴(b² - 1) - b⁴(b² - 1) = b⁴(a - 1)(b² - 1) =
b⁴(a - 1)(b + 1)(b - 1)