Bonjour j'ai besoin de l'aide pour ce devoir de 3e Merci 1)Développer et réduire A=(3x+2)² B=2x-(7x-2)² C=(y+6)(y-6) D=(-2x+5)(4x-3) 2) Factoriser si possible E

Bonsoir,

1) développer :

A = (3x + 2)^2
A = (3x)^2 + 2 * 3x * 2 + 2^2
A = 9x^2 + 12x + 4

B = 2x - (7x - 2)^2
B = 2x - (49x^2 - 28x + 4)
B = 2x - 49x^2 + 28x - 4
B = -49x^2 + 30x - 4

C = (y + 6)(y - 6)
C = (a + b)(a - b) = a^2 - b^2
C = y^2 - 36

D = (-2x + 5)(4x - 3)
D = -8x^2 + 6x + 20x - 15
D = -8x^2 + 26x - 15

2) factoriser :

E = x^2 - 8x + 16
E = (x)^2 - 2 * x * 4 + (4)^2
E = (x - 4)^2

F = x^2 - 7x + 49
F = pas factorisable

G = 9x^2 - 48x + 64
G = (3x)^2 - 2 * 3x * 8 + (8)^2
G = (3x - 8)^2

H = 81 - x^2
H = (9)^2 - (x)^2
H = (9 - x)(9 + x)

I = (x - 4)(x - 7) + (x - 4)(2x - 5)
I = (x - 4)(x - 7 + 2x - 5)
I = (x - 4)(3x - 12)
I = (x - 4) * 3(x - 4)
I = 3(x - 4)^2

J = (x + 2)^2 - 9
J = (x + 2)^2 - (3)^2
J = (x + 2 - 3)(x + 2 + 3)
J = (x - 1)(x + 5)