A function f:R→Rf: \mathbb{R} \to \mathbb{R}f:R→R satisfies f(x)f(y)−f(xy)=x+yf(x)f(y) - f(xy) = x+yf(x)f(y)−f(xy)=x+y. If f(2)=3f(2) = 3f(2)=3, find f(1)f(1)f(1).
1
2
0
3