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Pe R se considera legea de compozitie x⊥y=xy-x-y+2
a)Calculati (-2)⊥2
b)Sa se arate ca legea,,⊥'' este asociativa
c)Sa se rezolve in Recuatia x⊥x=1
DAU COROANA!


Răspuns :

a) (-2)⊥2=-4+2-2+2=-2
b) (x⊥y)⊥z= (xy-x-y+2)⊥z=xyz-xz-yz+2z-xy+x+y-2-z+2= xyz-xy-xz-yz+x+y+z
x
⊥(y⊥z)= x⊥(yz-y-z+2)=xyz-xy-xz+2x-x-yz+y+z-2+2= xyz-xy-xz-yz+x+y+z
deci legea e asociativa
c) xx-x-x+2=1
x
²-2x+1=0
(x-1)²=0
x=1

O zi buna!