约分：2xy-4y/x-2 a²-ab/a²-b² x²-9/9-6x+x²4-8b/4b²-1化简：（x+y）²/x²-y平方(1)2xy-4y/x-2(2)a²-ab/a²-b²(3)x²-9/9-6x+x²

约分：2xy-4y/x-2 a²-ab/a²-b² x²-9/9-6x+x²4-8b/4b²-1化简：（x+y）²/x²-y平方(1)2xy-4y/x-2(2)a²-ab/a²-b²(3)x²-9/9-6x+x²
约分：2xy-4y/x-2 a²-ab/a²-b² x²-9/9-6x+x²
4-8b/4b²-1
化简：
（x+y）²/x²-y平方
(1)2xy-4y/x-2
(2)a²-ab/a²-b²
(3)x²-9/9-6x+x²

约分：2xy-4y/x-2 a²-ab/a²-b² x²-9/9-6x+x²4-8b/4b²-1化简：（x+y）²/x²-y平方(1)2xy-4y/x-2(2)a²-ab/a²-b²(3)x²-9/9-6x+x²
2xy-4y/x-2 =2y(x-2)/(x-2)=2y
a²-ab/a²-b²=a(a-b)/(a+b)(a-b)=a/a+b
x²-9/9-6x+x²=(x+3)(x-3)/(x-3)²=x+3/x-3
4-8b/4b²-1=4(1-2b)/(2b+1)(2b-1)= -4(2b-1)/(2b+1)(2b-1)= -4/2b+1
(x+y)²/x²-y²=(x+y)²/(x+y)(x-y)=x+y/x-y