Réponses

2014-10-08T16:36:30+02:00
Bonjour,
A=x+y-2√(xy)=7-2*√4=7-4=3
B=2x-2xy+2y-4xy=2(x+y)-6xy=2*7-6*4=-10
C=(x-y+x+y)(x-y-x-y)=-2y*2x==-4xy=-4*4=-16