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