2 + 6 + 18 + 54 + ...
This is a geometric sum and there is a way to find the sum of however many terms as you would like.
The initial term is S1 = 2, the ratio of successive terms is r = 3.
The sum for a geometric sequence of the first n terms is given by
Sn = S1(1 - rn)/(1 - r)
Apply this formula for n = 10.
