lg((x-y)/2)^2=lg(xy),化简后得x2-2xy+y2=4xy,同除以4x2得,1/4+y/2x+y2/4x2=y/x令y/x=a,解得a=土2倍根号2+3,1/a=他的倒数,f(0)=0,a=1/(1+b),-f(1)=f(-1)=a-1/(2+b)=1/(0.5+b)-a,a=1,b=0