Bonjour, Développer les expressions suivantes : A = 3(x + 4) B = x(5 - y) C = -2(1 - x) D = (x + 1)(x - 2) Merci

Bonjour !

A = 3(x + 4)

= 3×x + 3×4

= 3x + 12

B = x(5 - y)

= x×5 - x×y

= 5x - xy

C = -2(1 - x)

= -2×1 - (-2)×x

= -2 + 2x

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

= (x + 1)×x + (x-1)×-2

= (x×x+x×1) + (-2×x+(-2)×-1)

= (x²+x) + (-2x+2)

= x² + x - 2x + 2

= x² - x + 2

Bonjour,

A = 3(x + 4)  = 3x+12

B = x(5 - y)  = 5x -xy

C = -2(1 - x)  = -2 +2x

D = (x + 1)(x - 2) = x² -2x +x -2 = x² -x -2