Final answer:
The 10th term of the sequence defined by the given rule is -253780.
Step-by-step explanation:
To find the 10th term of the sequence defined by the given rule, we can use the recursive formula. We know that f(1) = 20, and f(n) = 3 x f(n-1) - 80. To find the 10th term, we can use the formula recursively.
f(2) = 3 x f(1) - 80 = 3 x 20 - 80 = -20
f(3) = 3 x f(2) - 80 = 3 x (-20) - 80 = -140
Continuing this pattern, we find that the 10th term is f(10) = -253780.