f(1/x)=(1/x-1)/(1/x+1)=(1-x)/(1+x)=1-x/x+1所以f(x)+f(1/x)=0
1.因为 f(1/x)=(1/x-1)/(1/x+1)=(1-x)/(1+x)=-(x-1)/(x+1)=-f(x),所以 f(x)+f(1/x)=0 2. (1/x-1)/(1/x+1)=(1/x-1)/(x+1/1)=(x+1)/(x-1)