Rumus f(x) jika g(x) = x+2 dan (f•g) -¹ (x) = 2x + 3 adalah

g(x) = x+2
(fog)^(-1) (x) = 2x + 3
y = 2x + 3 → 2x = y-3 → x = (y-3)/2
maka (fog)(x) = (x-3)/2
(fog)(x) = (x-3)/2
f(g(x)) = (x+2-5)/2
f(g(x)) = (g(x)-5)/2
==> f(x) = (x-5)/2