Answer:
a(n) = -81(-4/3)^(n - 1)
Step-by-step explanation:
The first term is -81. From -81 we obtain the next term, 108, by multiplying -81 by -4/3. Note how (-4/3)(108) = -144 as anticipated.
Thus, the common ratio is -4/3.
The explicit function for this geometric series is
a(n) = -81(-4/3)^(n - 1)
