函数f(x)对一切x属于R^+,恒有f(x1,x2)=f(x1)+f(x2),若f(8)=3,则f(2^1/2)=?

函数f(x)对一切x属于R^+,恒有f(x1,x2)=f(x1)+f(x2),若f(8)=3,
f(8)=3f(2)=3
f(2)=1
f(2)=2f(2^1/2)=1
f(2^1/2)=1/2