Answer:
∑ₙ₌₁⁸ (3n − 9)
Step-by-step explanation:
This is an arithmetic series where the first term is -6 and the common difference is 3. The nth term can be written as:
aₙ = a₁ + d (n − 1)
aₙ = -6 + 3 (n − 1)
There are 8 terms in this series, so the sum is:
∑ₙ₌₁⁸ [-6 + 3 (n − 1)]
Simplified:
∑ₙ₌₁⁸ (3n − 9)
