e) -19 < 2x-1 < 19 /+1
-18 < 2x < 20 /:2
-9 < x < 10
x apartine (-9,10 ) iar -3 | x
E ={-6, -3, -1, 1,0, 1, 3, 6, 9}
f) x+2 apartine D13 iar D13 ={-13, -1, 1, 13 }
x+2 = -13 => x = -11 nu merge pt ca fractia 13/-9 nu apartine N
x+2 = -1 => x = -3 iar 13/ -1 nu merge
x+2 = 1 => x = x = -1 iar 13/1 = 13 apartine N
x+2 = 13 => x = 11 iar 13/13 = 1 apartine N
F = {-1, 11}