Answer:
The sequence is defined by the formula an = 3n(-2), where n is a positive integer. To determine if the sequence is increasing, decreasing, or not monotonic, we need to look at the difference between successive terms.
Let's calculate the first few terms of the sequence:
a1 = 3(1)(-2) = -6
a2 = 3(2)(-2) = -12
a3 = 3(3)(-2) = -18
The difference between successive terms is:
a2 - a1 = -12 - (-6) = -6
a3 - a2 = -18 - (-12) = -6
Since the difference between successive terms is always the same (-6), the sequence is decreasing, and the answer is B. decreasing.