a) x² - 12x - 45 = (x² - 12x + 36) - 36 - 45 = (x - 6)² - 81
б) (x - 6) - 81 = (x - 6)² - 9² = (x - 6 - 9)(x - 6 + 9) = (x - 15)(x + 3)
a) x² - 12x - 45 = (x² - 12x + 36) - 36 - 45 = (x - 6)² - 81
б) (x - 6) - 81 = (x - 6)² - 9² = (x - 6 - 9)(x - 6 + 9) = (x - 15)(x + 3)