若[1/2(x+y)]的二次方-[1/2(x-y)]的二次方
问题描述:
若[1/2(x+y)]的二次方-[1/2(x-y)]的二次方
答
原式=[1/2(x+y)+1/2(x-y)][1/2(x+y)-1/2(x-y)]
=xy