For a geometric sequence with a first term of "a" and a common ratio of "r", the n-th term is
.. an = a*r^(n-1)
For this problem, you have a = 8, r = -3, and n = 9. Filling these values into the formula gives
.. a9 = 8*(-3)^(9-1)
.. a9 = 8*(-3)^8
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a9 = 52,488