从2/1来看,估计是:2/(2x-4)-x/(x-2)=1/2
1/(x-2)-x/(x-2)=1/2
(1-x)/(x-2)=1/2
2(1-x)=x-2
2-2x=x-2
-2x-x=-2-2
-3x=-4
x=3/4