Bonjour,
A = 2(x - 1) + 2(y +2) - 2(1 + z)
= 2x -2 +2y + 4 -2 + 2z
= 2x + 2y + 2z
B = 3x - (3 - 3y ) + 3(z + 1)
= 3x -3 + 3y +3z + 3
= 3x + 3y + 3z
C= (x + y -1)+ (x + y + 1) - (x + y - z)
=x + y -1 +x +y +1 -x -y + z
= x +y + z
D= 2(x - y) + 3(y - z) +4 (z - x) + 3x
= 2x - 2y + 3y -3z +4z -4x +3x
= x + y + z
E = x(1 - y ) + y(1 - z) + z(1 - x) + xy + yz + xz
= x -xy +y -yz +z -xz +xy + yz +xz
= x + y + z
F= x - [(1-y)-(z + 1)]
= x -(1 - y - z -1)
= x -1 +y +z +1
= x + y + z
