Let f (x) be a function defined on the real number set R and satisfy the following conditions: F (x + 2) = f (x + 1) - f (x). If f (1) = Lg3 / 2, f (2) = LG15, find f (2004) Please! I'm very polite!

Let f (x) be a function defined on the real number set R and satisfy the following conditions: F (x + 2) = f (x + 1) - f (x). If f (1) = Lg3 / 2, f (2) = LG15, find f (2004) Please! I'm very polite!

because
f(x+2)=f(x+1)-f(x)
f(x+3)=f(x+2)-f(x+1)=f(x+1)-f(x)-f(x+1)=-f(x)
therefore
F (x) is a function of period 6
because
f(2004)=f(6*334+0)=f(0)
because
f(2)=f(1)-f(0)
lg15=lg3/2-f(0)
f(0)=-1