Question

What is the partial sum of the sum of negative 2 minus 8i for i equals 10 to 25 ?

Answer 1

\(\large \bf \Sigma_{i=10}^{25}\ -2-8i\implies S_{\color{red}{ n}}=\cfrac{{\color{red}{ n}}}{2}(a_1+a_{\color{red}{ n}})\)

I gather our \(a_1\) will be when "i=10" and our \(a_{25}\) will be when "i=25"

Answer 2

dosen't that mean a1 will be a10. and an will be a 25

Answer 3

so then a1=-82 and a25=-202

Answer 4

yes

Answer 5

then Sn=-3408

Answer 6

but my choices are +/-2208 and +/-2272

Answer 7

hmmm I get \(\bf \cfrac{25(-82-202)}{2}\implies \cfrac{25(-284)}{2}\implies -3550\)

Answer 8

maybe we're misreading iit
got a screenshot of it?