(根号x+根号y)²-(根号x-根号y)²=

问题描述:

(根号x+根号y)²-(根号x-根号y)²=


(√x+√y)²-(√x-√y)²
=[(√x+√y)-(√x-√y)][(√x+√y)+(√x-√y)]
=(2√y)(2√x)
=4√xy