Bonjour,
(x + 1)(x + 2) = x * x + x * 2 + 1 * x + 1 * 2 = x² + 2x + x + 2 = x² + 3x + 2.
Double distributivité
(x+1) (x+2)
x*x = x²
x*2 = 2x
1*x = x
1*2 = 2
=> x² +2x +x +2 = x +3x +2
