试说明代数式{(x-y)²-(x+y)(x-y)}÷(-1/2y)+4y的值,与y的值无关
问题描述:
试说明代数式{(x-y)²-(x+y)(x-y)}÷(-1/2y)+4y的值,与y的值无关
答
{(x-y)²-(x+y)(x-y)}÷(-1/2y)+4y
={2y^2-2xy}÷(-1/2y)+4y
=-4y+4x+4y
=4x