(1) (a+9b/3ab)-(a+3b/3ab)
问题描述：
(1) (a+9b/3ab)-(a+3b/3ab)
(2) (x/x+2)-(x/x-2)+(3x-2/x*x-4)
解方程：
（3）(x+1/x-2)+(1/x+1)=1
(4)(1/x+1)+(2/x-1)=1/x*x-1
答
(1)=(9-3)b/3ab=2a
(2)=[x(x-2)-x(x+2)+3x-2]/(x^2-4)
=-(x+2)/(x+2)(x-2)
=-1/(x-2)
(3)=[(x+1)^2+(x+1)-3]/(x+1)(x-2)=1
(x+1)^2+(x+1)-3=(x+1)(x-2)
(x+1)^2-(x+1)(x-3)-3=0
4x+1=0
x=-1/4
(4)
x-1+2x+2=1
3x=0
x=0