f(x,y)=(1/4)(x^2-y^2)
f(xy,x/y)=(1/4)[(xy)^2-(x/y)^2]=[x^2(y^4-1)]/[4y^2]那个，可以详细点给过程么，我数学实在不咋地，看不大懂怎么转换的。。因为f (x+y,x-y)=xy=(1/4)[(x+y)^2-(x-y)^2]所以 f(x,y)=(1/4)(x^2-y^2)f(xy,x/y)=(1/4)[(xy)^2-(x/y)^2]=(1/4)[(x^2*y^2-(x^2/y^2)]=[[x^2(y^4-1)]/[4y^2]