What is the sum of the first five terms of the geometric series 2 − 8 + 32 − . . ?

Now, is a geometric sequence, and sometimes called a "serie", but is just a sequence with a common "multiplier" or "common ratio".

so it goes from 2, to -8 and so on, to get the "common ratio" you just simply divide a further term by another, -8/2 = -4  <--- r



and surely you'd know how much that is.

9.8? i'm not really sure