Is the following sequence
arithmetic or geometric? 11, 33, 99, 297, and so on.
Well, if we were adding we would
get- have to add different numbers each time to get the next number in the
sequence. But if we multiply each term by
three, we generate the next term. So we’ve got a common ratio of
three. So the fact that we’ve got a common
ratio rather than a common difference tells us that we got a geometric sequence.