Esercizi
[0DW] Data una serie \(β_ n^β a_ n\) dire se le condizioni successive sono necessarie e/o sufficienti per la convergenza.
\begin{eqnarray} β\varepsilon {\gt}0~ β mβ{\mathbb {N}}~ β n{\gt}m ~ β kβ{\mathbb {N}}~ ~ \left|β_{j=n}^{n+k} a_ k\right|{\lt}\varepsilon \\ β\varepsilon {\gt}0~ β kβ{\mathbb {N}}~ β m β{\mathbb {N}}~ β n{\gt}m ~ \left|β_{j=n}^{n+k} a_ k\right|{\lt}\varepsilon \\ β\varepsilon {\gt}0~ β mβ{\mathbb {N}}~ β n{\gt}mβ kβ{\mathbb {N}}~ ~ β_{j=n}^{n+k} |a_ k| {\lt}\varepsilon \\ β\varepsilon {\gt}0~ β kβ{\mathbb {N}}~ β mβ{\mathbb {N}}~ β n{\gt}m ~ β_{j=n}^{n+k} |a_ k|{\lt}\varepsilon \end{eqnarray}1