La A se observa ca x apartine [-3, +infinit)
adica A={-3 , -2 , -1, 0,1....}
La B x apartine (-2, 3] deci B={-1, 0,1,2,3]
A={-3 , -2 , -1, 0,1....(infinit)}
B={-1, 0,1,2,3]
