bonjour
Il faut remplacer les lettres par leur valeur
A = x - y + z
A = 5/6 - ( - 7/3 ) + ( - 19/18 )
A = 15/18 + 42/18 - 19/18
A = 38/18 = 19/9
B = x + y + z
B = 5/6 - 7/3 - 19/18
B = 15/18 - 42/18 - 19/18
B = - 46/18 = - 23/ 9
C = x - ( y - z)
C = 5/6 - [( - 7/3 - ( - 19/18 ) ]
C = 15/18 - ( - 42/18 + 19/18 )
C = 15/18 + 42/18 - 19/18
C = 38/18 = 19/9
D = x - ( y + z)
D = 5/6 - ( - 7/3 - 19/18)
D = 15/18 - ( - 26/18 )
D = 15/18 + 26/18
d = 41/18
