Réponses

2014-05-26T17:36:09+02:00
1)
DA+BC+CD=DA+BD=BA

2)
AB+BC-CD+DA=AC+DC+AD=AC+AC=2AC

3)
AC+2CB+BA=BA+AC+2CB=BC+2CB=-CB+2CB=CB

4)
AM+NP-AD+MN-BP+BC=DA+AM+MN+NP+PB+BC=DM+MP+PC=DP+PC=DC