Bonsoir,
Développer :
A = (x - 3)(1 - y)
A = x*1 + x*(-y) + (-3)*1 + (-3)*(-y)
A = x - xy - 3 + 3y
A = -xy + 3y + x - 3
B = (3 - x)(4 + x)
B = 3*4 + 3*x + (-x)*4 + (-x)*x
B = 12 + 3x - 4x - x²
B = -x² - x + 12
C = (2x - 4)(x + 1)
C = 2x*x + 2x*1 + (-4)*x + (-4)*1
C = 2x² + 2x - 4x - 4
C = 2x² - 2x - 4
* = multiplication
Bonne soirée.
