Answer:

n = n

First term, a = a₁ = (x-y)/(x+y)

Common difference, d = a₂ – a₁ = (3x – 2y)/(x + y) – (x-y)/(x+y) = (2x – y)/(x+y)

By using the formula,

S = n/2 (2a + (n – 1) d)

Substitute the values of ‘a’ and ‘d’, we get

S = n/2 (2((x-y)/(x+y)) + (n-1) ((2x – y)/(x+y)))

S = n/2(x+y) {n (2x-y) – y}

∴ The sum of the given AP is n/2(x+y) {n (2x-y) – y}