5) 12a²b³ - 18a⁵b² = 6a²b²(2b - 3a³)
6) 8x + 8y - ax - ay = (8x + 8y) - (ax + ay) = 8(x + y) - a(x + y) = (x + y)(8 - a)
3) (b² - 7)² - b(b² - 7) = (b² - 7)(b² - 7) - b(b² - 7) = (b² - 7)(b² - 7 - b)
4) 8m⁷ - 6m²n - 12m⁵n³ + 9n⁴ = (8m⁷ - 6m²n) - (12m⁵n³ - 9n⁴) =
= 2m²(4m⁵ - 3n) - 3n³(4m⁵ - 3n) = (4m⁵ - 3n)(2m² - 3n³)