Разложите на множители: 1) b³ - 8c³; 2) 49x²y - y³; 3) -7a² + 14a – 7; 4) 5ab - 15b – 5a + 15; 5) a⁴ - 1.

1) b³ - 8c³ = b³ - (2c)³ = (b - 2c)(b² + 2bc + 4c²) 2) 49x²y - y³ = y(49x² - y²) = y(7x - y)(7x + y) 3) -7a² + 14a – 7 = -7(a² - 2a + 1) = -7(a - 1)² 4) 5ab - 15b – 5a + 15 = 5b(a - 3) - 5(a - 3) = (5b - 5)(a - 3) = 5(b - 1)(a - 3) 5) a⁴ - 1 = (a²)² - 1² = (a² - 1)(a² + 1) = (a - 1)(a + 1)(a² + 1)