What are the explicit equation and domain for a geometric sequence with a first term of 2 and a second term of -8
a) an = 2(-8)^ n-1; all integers where n > 1
b) an = 2(-8)^ n-1; all integers where n > 0
c) an = 2(-4)^ n-1; all integers where n > 0
d) an = 2(-4)^ n-1; all integers where n > 1