数学分式计算～～急～～高手进

1、3/x+2+1/2-x
=3/(x+2)-1/(x-2)
=[3(x-2)-(x+2)]/(x+2)(x-2)
=(2x-8)/(x^2-4)
2、x+2y/x^2-y^2 + y/y^2-x^2 - 2x/x^2-y^2
=(x+2y-y-2x)/(x^2-y^2)
=(y-x)/(x+y)(x-y)
=-1/(x+y)
3、x+2/x^2-2x - x-1/x^2-4x+4
=[(x+2)(x-2)-(x-1)x]/x(x-2)^2
=(x-4)/[x(x-2)^2]
4、x^2/x-1-x-1
=[x^2-(x+1)(x-1)]/(x-1)
=1/(x-1)

一看见就马上失望了,太简单,你还是自己来吧