16-8(x-y)+(x-y)^2 是等于(x-y-4)^2还是(4-x-y)^2
问题描述:
16-8(x-y)+(x-y)^2 是等于(x-y-4)^2还是(4-x-y)^2
书上是前一个 但我算怎么弄都是第2个
答
16-8(x-y)+(x-y)²
=[4-(x-y)]²
=(4-x+y)² 第二个是错
=(x-y-4)² 第一个是对
16-8(x-y)+(x-y)²
=(x-y)²-8(x-y)+16
=(x-y-4)²