Se considere expresia E(x)=([tex] \frac{x}{x+1} - \frac{2}{x-1}[/tex]):[tex] \frac{ x^{2}+x +2 }{ x^{4}- x^{2} } [/tex]   , unde x apartine R /{ -1 0 1}. Demonstrati ca E(x)= [tex] x^{2} [/tex],∨( A intors) care apartine R/ { -1 0 1}