Write the First Four Terms for Each Sequence $a_{n}=(n+1)(n-2)$ (B) $a_{n}=\left(-\frac{1}{4}\right)^{n-1}$ (C) $a_{1}=2, a_{2}=6, a_{n}=2 a_{n-1}-a_{n-2}$

Short Answer

Write the first four terms for each sequence. State whether the sequence is arithmetic, geometric, or neither.
(a) $a_{n}=(n+1)(n-2)$
(b) $a_{n}=\left(-\frac{1}{4}\right)^{n-1}$
(c) $a_{1}=2, a_{2}=6, a_{n}=2 a_{n-1}-a_{n-2}$ , for $n \geq 3$