Răspuns :
E (X)= (X-7)(X+7)/X(X-7) - 2X+7/X(X+1)*X+1
se simplifica x-7/x-7 dar si x+1 cu x+1 si obtinem
E(x) = x+7/x - 2x+7/x=x-2x+7-7/x = -x/x=-1
se simplifica x-7/x-7 dar si x+1 cu x+1 si obtinem
E(x) = x+7/x - 2x+7/x=x-2x+7-7/x = -x/x=-1