Summen I.13

$$\sum_{k=1}^{n}a_{k}+\sum_{k=1}^{n}b_{k}=\sum_{k=1}^{n}\left(a_{k}+b_{k}\right)$$

$$\sum_{k=1}^{n}a_{k}=\sum_{k=1}^{m}a_{k}+\sum_{k=m+1}^{n}a_{k}\quad1\leq m\leq n$$

Indexverschiebung:

$$\sum_{k=a}^{b}g_{k}=\sum_{k=a+c}^{b+c}g_{k-c}$$