Question

HELP Use the values of a, and S, to find the value of an.
a₁ = 8 and S40 = 6960; a40
a40

Answer 1

a₄₀=340

Explanation:

Sₙ=[(a₁+aₙ)/2]*n

a₁=8 n=40 S₄₀=6960

S₄₀=[(a₁+a₄₀)/2]*40

6960=[(8+a₄₀)/2]*40 /:40

174=(8+a₄₀)/2 /*2

348=8+a₄₀

a₄₀=340