Respuesta :
so when there is f(x) = 2 without unknowed term of x so this mean that for indifferent value of x the result is 2
for f(2) you need to know f(x) = ? and than just you need substituting the 2 in place of x and calculi the result what will be f(2) = ?
f(x) you dont know what x is or f but in f(2) you know that what would be x is 2