F(x)+2xf(1/x) = 3(x+1). Maka f(2015) =…..

F(x) + 2(x). f(1/x) = 3(x+1) ……..(1)
f(1/x) + 2(1/x) f(x) = 3(1/x +1) —>   2/x . f(x) + f(1/x) = 3(1/x +1) …..(2)

(1) dan (2) eliminasi

f(x) + 2x . f(1/x) = 3(x+1)
2/x . f(x) + f(1/x) = 3(1/x  + 1) …..kalikan 2x
…
f(x) + 2x . f(1/x) = 3(x+1)
4. f(x) + 2x . f(1/x) = 6(x+1)
kurangkan
3.f(x)  = 3(x+1)
f(x) = x + 1

f(2015) = 2015 +1 = 2016