Question

Find an explicit rule for the nth term of the sequence.

2, -8, 32, -128, ...

Answer 1

Would the answer be a_n = 2 * (-4)^n or a_n = 2 * (-4)^n-1? I picked the first one but I just want to be sure.

Answer 2

@iGreen

Answer 3

The second one.

Answer 4

Since that's what the formula states.

Answer 5

your sequence is a geometric sequence, with first term=2, and constant=-4,
so:
\[a _{n}=a _{1}q ^{n-1}=2*(-4)^{n-1}\]

Answer 6

Thank you @Michele_Laino

Answer 7

Thank you! @sunshine201