Réponse :
Bonjour,
Avec relation de Chasles:
a) CD-AD = CD + DA
= CA
b) AB-AC = BA - AC
= BC
c) AB- DB-AD = AB - BD - AD
= AD - AD
= 0
d) AB - DC + BC = AB - DC + CB
= AB - DB
= AB - BD
= AD
e) AC +2CB+BA = AC + CB + CB + BA
= AB + CA
= CA + AB
= CB
f) 2 AB-BC - CA =2AB + CB + AC
= 2AB + AC + CB
= 2AB + AB
= 3AB