Bonjour j'aurai besoin d'aide pour le 87 merci D'avance

A = 5x + 2x
B = 6x + x

a) Calculer A et B pour x = 1
A = 5x + 2x
A = 5 * 1 + 2 * 1
A = 5 + 2
A = 7

B = 6x + x
B = 6 * 1 + 1
B = 6 + 1
B = 7

Calculer A et B pour x  = 2
A = 5x + 2x
A = 5 * 2 + 2 * 2
A = 10 + 4
A = 14

B = 6x + x
B = 6 * 2 + 2
B = 12 + 2
B = 14

b) On remarque que A = B

c) A = 5x + 2x = 7x
B = 6x + x = 7x
7x = 7x
Donc
A = B pour toute valeur de x

2) C = x (x - 1)
D = 2x - 2

a) Calculer C et D pour x = 1
C = x (x - 1)
C = 1 (1 - 1)
C = 1(0)
C = 0

D = 2x - 2
D = 2 * 1 - 2
D = 2 - 2
D = 0

Calculer C et D pour x = 2
C = x (x - 1)
C = 2 (2 - 1)
C = 4 - 2
C = 2

D = 2x - 2
D = 2 * 2 - 2
D = 4 - 2
D = 2

b) On remarque que C = D

c) C = x (x - 1)
C = x² - x

D = 2x - 2

x² - x ≠ 2x - 2
Donc
C ≠ D