若x2-2xy-y2-x+Y-1=0 求x-y的值
问题描述：
若x2-2xy-y2-x+Y-1=0 求x-y的值
答
x-y=(1+√5)/2或x-y=(1-√5)/2
答
x²-2xy+y²-x+y-1=0
(x-y)²-(x-y)-1=0
[x-y-(1+√5)/2][x-y-(1-√5)/2]
所以x-y=(1+√5)/2或x-y=(1-√5)/2