Partea imaginara a lui (1 + z) / z trebuie sa fie 0
[tex] \frac{1+z}{z}= \frac{x + 1 + iy}{x+iy}= \frac{(x+1+iy)(x-iy)}{x^2+y^2}= \frac{x(x+1)+y(x-x-1)i+y^2}{x^2+y^2}= \frac{x(x+1)+y^2-yi}{x^2+y^2} \\
Im(\frac{x(x+1)+y^2-yi}{x^2+y^2})= \frac{yi}{x^2+y^2}=0 \rightarrow y=0 [/tex]
C = R X {0}