``(x-2倍根号xy+y)(根号x +根号y)

问题描述:

``
(x-2倍根号xy+y)(根号x +根号y)

(x-2倍根号xy+y)*(根号x +根号y)
=(根号x -根号y)^2*(根号x +根号y)
=(x-y)(根号x -根号y)