Express the series using sigma notation. -8 + 4 - 2 + 1.

-12

Step-by-step explanation:

I believe you want the "sum of the series," because that's what you get from "sigma notation."  Two cases here:  infinite series and partial series.

If you wish to find the sum of the infinite series whose first term is a = -8 and whose common ratio is r = (-1/2), use the formula

                                             a

sum of infinite series =

                                          1 -  r

which here comes to

                                              -8

sum of infinite series = = -8/(3/2) = -12

                                         1 - (-1/2)

$12. that is my answer.