Question

what is the 20th term of the sequence that begins with -3, 6, 12, 24,......?

Answer 1

I always write out the difference in an addy kind of way, then in a timesy kind of way. It's easier to spot patterns, i think.
ie -3 to 6 = 9
so
9, 6, 12 ...

in a timesy kind of way
-3 * -2 = 6
6 * 2 = 12
12 * 2 = 24
so
-2, 2, 2

Are you sure it a -3?

Answer 2

sorry forgot to reply. but yes, i wrote the problem wrong. it is -3, 6, -12, 24 @doc.brown

Answer 3

-2, -2, -2, -2 in a timesy sort of way.