[tex]\displaystyle E(x)=\left(x-1- \frac{x^2}{x+2} \right): \frac{x-2}{x+2} \\ \\ E(x)= \frac{x(x+2)-(x+2)-x^2}{x+2} : \frac{x-2}{x+2} \\ \\ E(x)= \frac{x^2+2x-x-2-x^2}{x+2} \cdot \frac{x+2}{x-2} \\ \\ E(x)= \frac{x-2}{x+2} \cdot \frac{x+2}{x-2} \\ \\ E(x)=1[/tex]
