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