Use the formula to evaluate the series 3-9+27-81 + ... - ae

(-4920)

Step-by-step explanation:

we see that the first term is 3 and the common ratio between the succeeding terms is - 3. so to solve for the sum of the first 8 terms

Sum = (a1) (1 - r^n) / (1 - r)

and substituting the known terms, we got

Sum = (3) (1 - (-3) ^8) / (1 - (-3)) = - 4920

Then the answer = (-4920)