\(\sum_{i=1}^{n}c = n c\)
\(\sum_{i=1}^{n}c a_i = c\sum_{i=1}^{n}a_i\)
\(\sum_{i=1}^{n}a_i \pm b_i = \sum_{i=1}^{n}a_i \pm \sum_{i=1}^{n}b_i\)