Which formula can be used to describe the sequence? -2/3, −4, −24, −144, a) f(x) = 6(-2/3)^x-1 b) f(x) = -6(2/3)^x-1 c) f(x) = 2/3 (6)^x-1 d) f(x) = 2/3 (-6)^x-1

Remark
The closest answer is D, but the answer has to be rewritten: f(x) = - 2/3 (6)^(x - 1) where x is 1,2,3,4,5,6 to plus infinity.  If that is not what you are given, there is no answer.

Discussion
The  minus sign is misplaced. There are 2 reasons. 
1. When x is odd, then the minus sign is not there and every other term will be plus.
2. For a related reason, you cannot get a minus 2/3 if the sign is affected by the power. The first term must be -2/3. (-6)^0 power is 1 not -1

There is no answer, but you could try C if D does not work.