Question

1. an= suma de n , k=1 ∑ $\frac{1}{(k+1)(k+3)}$ , an=?
2. an= suma de n, k=1 ∑$\frac{1}{k(k+1)(k+2)}$ , an=?
3.an=$\frac{1}{2!} + \frac{2}{3!}+ \frac{3}{4!}+...+ \frac{n}{(n+1)!}$ , an=?

Answer 1

La punctul 2, trebuie scrisi mai multi termeni pentru a orserva toate reducerile.