Question

Calculati |x| + |y| , stiind ca |x+y+2| + |x-y| = 0

Answer 1

egalitatea din enunt presupune:
|x+y+2|=0 si
|x-y|=0 ⇒ x=y
2y+2=0
y= -1
x= -1

Answer 2

Relatia a doua e adevarata doar daca Ix+y+2I=0 si Ix-yI=0, rezulta x=y si x+x+2=0, adica x=-1=y
Deci IxI+IyI=1+1=2