Express the sum in sigma notation: 1 - 3 + 9 - 27 + 81

I guess it wiil be solved like this

So based on your question that ask to express the sum of sigma notation of 1-3+9-27-81 and based on my calculation and the use of formula and laso the use of your given i came up with an answer of K=1 and i hope you are satisfied with my answer