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