(x-y）²-2x+2y+1怎么算,读出来是x-y的平方减去2x+2y+1要快,要快!急救拜托!
问题描述：
(x-y）²-2x+2y+1怎么算,读出来是x-y的平方减去2x+2y+1要快,要快!急救拜托!
答
我致命的危险,
(x-y）²-2x+2y+1
=(x-y）²-2（x-y）+1
=（x-y-1）²