Question

PLEASE HELP!! What are the explicit equation and domain for a geometric sequence with the first term of 3 a second term of -9?

Answer 1

the third option

Explanation:

a1 = 3

a2 = -9

as a geometric sequence every sequence item is created by multiplying a constant factor with the previous item.

what do I need to multiply 3 with to get -9 ? right, -3.

so, the first 2 options are out, because they multiply with -12.

and we can accept only n>=1, because there is no a0. it starts with a1.

ah only the third option is right.