Arithmetic Sequence

Question

Find the sum of the first 30 terms of the arithmetic sequence with the first term 3 and common difference 8.

Answer 1

A_n = A₁+ (n - 1)d A₃₀ = 3 + 29x8 = 235

S₃₀ = (n/2)(a₁ + a_n) S₃₀ = (30/2)(3 + 235) = 3570