已知x>y,且x+y=5,xy=4,求根号x+根号y分之根号x-根号y.
问题描述:
已知x>y,且x+y=5,xy=4,求根号x+根号y分之根号x-根号y.
答
(根号x-根号y)/(根号x+根号y)
=根号【(x+y-2根号(xy))/(x+y+2根号(xy))】
=根号【(5-4)/(5+4)】
=1/3