[1/(x-y)-1/(x+y)]/[2y/(x^2-2xy+y^2)]={[(x+y)-(x-y)]/[(x+y)(x-y)]}*(x^2-2xy+y^2)/2y={2y/[(x+y)(x-y)]}*{(x-y)^2/2y}=(x-y)/(x+y）x=1+根号2,y=1-根号2,代入原式=【(1+根号2）-（1-根号2)】/【(1+根号2）+（1-根...