If you have a series: 1^2 - 3^2 + 5^2 - 7^2 +... (-1)^(n-1)(2n-1)^2 how can you find a formula to represent the sum of the series. I have absolute no idea how to approach this question. The textbook doesn't show any examples of question where the found an equation for the sum of a series. They have a question however that is similar to this, that is for the series: 1^2 + 3^2 + 5^2 + 7^2 + 9^2+...(2n-1)^2, the sum is: (n/3)(2n-1)(2n+1) I don't know how or if that helps. The textbook actually says to "guess" a summation formula and than prove it. So, any help would be appreciated.