Question

The formula S=

2S-a, n
Oan=- n
n(a₁ + an)
2
2S+ a₁n
an-- n
an-2S+a, n+n
a, 2S-a, n+n
gives the partial sum of an arithmetic sequence. What is the formula solved for a,,?

Answer 1

2S-a1n/n

Explanation:

S = n(a1 + an)/2

2S = n(a1 + an)

2S = na1 + nan

nan = 2S - na1

an = (2S - n a1)/n