Question

what is S7 for 6-24+96-384+...?

Answer 1

how are the numbers aranged?
arithmatic series
or geometric series?

Answer 2

ie., do the successive numbers have a common difference or a common ratio?

Answer 3

it is a G.P with r=-4
@nicole-0109

Answer 4

@electrokid is arithmatic series

Answer 5

how can you make that claim?

Answer 6

arithmatic series = successive terms have a constant difference
geometric series = successive terms have a constant ratio

Answer 7

so, like gorv said, the successive terms have a constant ratio of "-4"
then we use the formula for sum to n^th term of a geometric series
\[S_n=a_0\frac{1-r^n}{1-r}\]
plug in the numbers and solve

Answer 8

i got -4914??

Answer 9

what numbers did you plug in?