Question

.（x-y/x+y）²÷（y-x/x²+2xy+y²）•1/x+y，其中x=-4，y=1。

要有过程解答。

Answer 1

原式=（x-y/x+y）²*(x+y）²/(y-x)(y+x)
约分得(y-x)/(y+x)
将x=-4，y=1代入得原式=-5/3

Answer 2

原式=[(x-y)²/(x+y)²]×[-(x+y)²/(x-y)]×1/(x+y)
=-(x-y)/(x+y)
=-(-4-1)/(-4+1)
=-5/3