Bonjour,
Il suffit de connaître ses identités remarquables : a² - b² = (a + b)(a - b)
A = 100x² - 81
A = (10x + 9)(10x - 9)
B = (2x + 1)² - 4
B = [(2x + 1) + 2][(2x + 1) - 2]
B = (2x + 3)(2x - 1)
C = 16x² - 25 + (3x - 8)(4x + 5)
C = (4x + 5)(4x - 5) + (3x - 8)(4x + 5)
C = (4x + 5)[(4x - 5) + (3x - 8)]
C = (4x + 5)(4x - 5 + 3x - 8)
C = (4x + 5)(7x - 13)
D = 3x² - 5x
D = x(3x - 5)
E = 15x - 20
E = 5(3x - 4)
Bonne journée !
