Bonjour,
A = 12x - 30 = 6 × 2x - 6 × 5 = 6 × (2x - 5)
B = 15x² - 18x = 3x × 5x - 3x × 6 = 3x × (5x - 6)
C = 27x² - 3 = 3 × 9x² - 3 × 1 = 3 ×(9x² - 1)
