解
f(1/9)=f(1/3*1/3)=2f(1/3)=2f(3*1/9)=2[f(3)+f(1/9)]=2f(3)+2f(1/9)
f(9)=f(3*3)=2f(3)
f(1/9)=f(9)+2f(1/9)
f(9)=-f(1/9)
所以f(1/9)/f(9)=-1
解
f(1/9)=f(1/3*1/3)=2f(1/3)=2f(3*1/9)=2[f(3)+f(1/9)]=2f(3)+2f(1/9)
f(9)=f(3*3)=2f(3)
f(1/9)=f(9)+2f(1/9)
f(9)=-f(1/9)
所以f(1/9)/f(9)=-1