1) a³ + 8b³ = a³ + (2b)³ = (a + 2b)(a² - 2ab + b²)
2) x²y - 36y³ = y(x² - 36y²) = y(x - 6y)(x + 6y)
3) - 5m² + 10mn - 5n² = - 5(m² - 2mn + n²) = - 5(m - n)² = - 5(m - n)(m - n)
4) 4ab - 28b + 8a - 56 = (4ab + 8a) - (28b + 56) = 4a(b + 2) - 28(b + 2) =
= (b + 2)(4a - 28) = 4(b + 2)(a - 7)
5) a⁴ - 81 = (a²)² - 9² = (a² - 9)(a² + 9) = (a - 3)(a + 3)(a² + 9)