Verified answer

Bonsoir,

Rappel des identités remarquables :

(a + b)² = a² + 2ab + b²

(a - b)² = a² - 2ab + b²

(a - b)(a + b) = a² - b²

2) A = (x + 2)²

A = x² + 4x + 4

B = (3 - x)²

B = 9 - 6x + x²

C = (7x + 4)²

C = 49x² + 56x + 16

D = (5x - 6)²

D = 25x² - 60x + 36

E = (2x + 3)(2x - 3)

E = 4x² - 9

Exercice 2  :

(2x - 5)² + (3x + 7)(2x - 5)

= (4x² - 20x + 25) + (6x² - 15x + 14x - 35)

= 4x² - 20x + 25 + 6x² - x - 35

= 10x² - 21x - 10