# summation

• February 2nd 2009, 08:04 AM
summation
Why is $
\sum^{n}_{r=1}(4r^2-4r+1)=4\sum^{n}_{r=1}r^2-4\sum^{n}_{r=1}r+\sum^{n}_{r=1}1 ??

$

It looks like expansion but i don think it is ...
• February 2nd 2009, 08:17 AM
o_O
These properties hold for summations:
• $\sum_{k = 1}^n \left(a_k \pm b_k\right) = \sum_{k=1}^n a_k \pm \sum_{k=1}^n b_k$
• $\sum_{k = 1}^n ca_k = c\sum_{k=1}^n a_k$ where $c$ is a constant

See how these apply to your summation?