Bonjour J’aurais besoin d’aide en mathématiques niveau 3eme , merci d’avance

A = (x+4)(2x-5)
= 2x^2 - 5x + 8x - 20
= 2x^2 + 3x - 20

B = (5x + 3)^2
= 25x^2 + 30x + 9

C = (6 - 2x)^2
= 36 - 24x + 4x^2

D = (3x - 7)(3x + 7)
= 9x^2 - 49


E = 4x - 4
= 4(x - 1)

F = 7x^2 + 5x
= x(7x + 5)

G = -2x^2 + 2
= 2(-x^2 + 1)

H = (x + 1)(x - 2) + (3 - x)(x + 1)
= -(x +1)

Ex 2
a)
(x + 1)(x - 7) = 0
x + 1 = 0 ou x - 7 = 0
S = {-1 ; 7}

b)
16x^2 - 9 = 0
(4x - 3)(4x + 3) = 0
S = {-3/4 ; 3/4}

c)
x^2 + 6x + 9 = 0
(x + 3)(x + 3) = 0
S = {-3}