a) 3c² - 3d² = 3(c² - d²) = 3(c - d)(c + d)
б) 6ab² - 6ac² = 6a(b² - c²) = 6a(b - c)(b + c)
в) 20 - 45x² = 5(4 - 9x²) = 5(2 - 3x)(2 + 3x)
г) 16a⁵ - a³ = a³(16a² - 1) = a³(4a - 1)(4a + 1)