(1-2/x)^(-1)=x/(x-2)=1+2/(x-2),
x趋向于无穷,x-2 趋向于无穷,2/(x-2)趋向于0,
lim(x趋向于无穷)(1-2/x)^(-1)=1.
(其实应考虑x趋向于正无穷和负无穷的情况)