Respuesta :

fof(x) = f(x^2 - x) = (x^2 - x)^2 - (x^2 - x)
f(3) = (9 - 3)^2  - (9 - 3)
f(3) = 6^2 - 6
f(3) = 36 - 6 = 30

I wouldn't want to bet the farm on this. If you get another answer that is reasonable, take it.