已知X=2+根号3分之1,XY等于1,则X方减Y方分之X方Y减XY方等于?
问题描述：
已知X=2+根号3分之1,XY等于1,则X方减Y方分之X方Y减XY方等于?
答
x=1/(2+√3)
xy=1
y=(2+√3)
x=1/(2+√3)
x=(2-√3)/(2+√3)(2-√3)
x=2-√3
(x^2y-xy^2)/(x^2-y^2)
=xy(x-y)/(x+y)(x-y)
=xy/(x+y)
=1/(2-√3+2+√3)
=1/4