Determine if the sequence is geometric. If it is, find the common ratio, the 8th term, the explicit formula, an the recursive formula. 7) -1, -3, -9, -27,... 8) -1, -6, -36, -216, ... 9) 3, 18, 108, 648, ... 10) -4, -8, -16, -32, ... 11) -1, 2, -4, 8, ... 12) 1, -3, 9, -27