Properties of summation:
- sum(c * ) = c * sum() (constant factor)
- sum( + ) = sum() + sum() (linearity)
- c = nc (sum of a constant)
- = - (splitting range)
Decomposition technique: Express the general term as a sum of standard forms: = + + Ck + D Then sum = Asum() + Bsum() + Csum(k) + Dn
Example: sum of k(k+1)(k+2) = sum( + 3 + 2k) = [n]^2 + 3n(n+1) + 2n. But it's faster to use the direct formula n(n+1)(n+2).