State whether each recursive formula defines a sequence that is arithmetic, geometric, shifted geometric, or none of

Question:

State whether each recursive formula defines a sequence that is arithmetic, geometric, shifted geometric, or none of these. State whether a graph of the sequence would be linear or curved. Then list the first 5 terms of the sequence.
a. u1 = 4 and un = 3un - 1 where n ≥ 2
b. u0 = 20 and un = 2un - 1 + 7 where n ≥ 1