Răspuns:
Explicație pas cu pas:
[tex]E(x)=\dfrac{x}{x(x+1)}-\dfrac{x(x+1)-x(x-1)}{(x-1)(x+1)} :\dfrac{2x}{x-1} =\dfrac{1}{x+1} -\dfrac{x(x+1-x+1)}{(x-1)(x+1)} *\dfrac{x-1}{2x}=\dfrac{1}{x+1} - \dfrac{2x}{(x-1)(x+1)}*\dfrac{x-1}{2x}= \dfrac{1}{x+1}-\dfrac{1}{x+1}=0[/tex]
