Question

What is the sum of the geometric sequence -1, 6, -36, … if there are 7 terms

Answer 1

\[S7=-1.((-6)^{7}-1)/(-6-1)\]

Answer 2

{-1, 6, -36, 216, -1296, 7776, -46656}
Sum=-39991

Answer 3

thanks

Answer 4

Or you can doit as suggested above as
\[
S_7=-1\frac{1-(-6)^7}{1+6}=-3999
\]