Sum In Closed Form - Web to derive the closed form, it's enough to remember that $\sum_{i=1}^{n} i=\frac{n(n+1)}{2}\,$, then for example:.
Web to derive the closed form, it's enough to remember that $\sum_{i=1}^{n} i=\frac{n(n+1)}{2}\,$, then for example:.