# Math Help - Sigma Notation. I got the answer but still a little bit confused how i got there.

1. ## Sigma Notation. I got the answer but still a little bit confused how i got there.

Can some one please help me with this question? I have answered it already although do not understand each stage. Such as the first 8 for example. Rather than carry on I would like some clarification on how I got there and why.

2. ## Re: Sigma Notation. I got the answer but still a little bit confused how i got there

Hey camorris.

The big hint is knowing that (-1)^2r = 1 for all integer values of r and (-1)^(2r+1) = -1 again for all integer values of r.