Now plug in x = 3:
The answer is (D).
SEQUENCES FORMULAS
If d is the difference from one term to the next, a 1 is the first term, an is the nth term, and Sn
is the sum of the first n terms:If r is the ratio between consecutive terms, a 1 is the first term, an is the nth term, and Sn is the
sum of the first n terms:Arithmetic Sequences:Geometric Sequences: