说明代数式[(x-y)²-(x+y)(x-y)]÷(-2y)+y的值,与y的值无关

说明代数式[(x-y)²-(x+y)(x-y)]÷(-2y)+y的值,与y的值无关

[(x-y)²-(x+y)(x-y)]÷(-2y)+y=[(x-y)（x-y-x-y)]÷(-2y)+y=-2y（x-y）÷(-2y)+y=x-y+y=x
化简以后只有x,

[(x-y)²-(x+y)(x-y)]÷(-2y)+y
=[x²+y²-2xy-x²+y²]÷(-2y)+y
=2y(y-x)÷(-2y)+y
=x-y+y
=x
故结果与y值无关。