In the given series, we see that the first term is 3 and the common ratio between the succeeding terms is -3. To solve for the sum of the first 8 terms, we use the equation,
Sum = (a1)(1 – r^n) / (1 – r)
Substituting the known terms,
Sum = (3)(1 – (-3)^8)/(1 - -3) = -4920
Thus, the answer is -4920.