Răspuns :
Aduci la acelasi numitor si faci operatiile
(n+1)/n*(n+1)-n/(n+1)*n=(n+1-n)/n*(n+1)=1/n*(n+1)
(n+1)/n*(n+1)-n/(n+1)*n=(n+1-n)/n*(n+1)=1/n*(n+1)