prima fractie
x/(x^3+x^2)=x/x^2(x+1)=1/x(x+1)
a doua fractie, dupa ce desfacem parantezele va fi
(2x^2+4x-x-2-x^2-3x+1) / 6(x+1)(x-1)=(x^2-1)/6(X^2-1)=1/6
dupa inmultirea primei fractii cu a doua inversata obtinem
E(x)=1/x(x+1) * 6=6/[x(x+1)] ceea ce trebuia demonstrat!
