请注意括号的正确使用,以免造成误解.
方法一:
[x/(x-2)-x/(x+2)][(2-x)/x]
=[1/(x-2)-1/(x+2)](2-x)
=-1-(2-x)/(x+2)
=[-(x+2)-(2-x)]/(x+2)
=(-x-2-2+x)/(x+2)
=-4/(x+2).
方法二:
[x/(x-2)-x/(x+2)][(2-x)/x]
=[1/(x-2)-1/(x+2)](2-x)
={[(x+2)-(x-2)]/[(x-2)(x+2)]}(2-x)
={4/[(x-2)(x+2)]}(2-x)
=-4/(x+2).
注:若原题不是我所猜测的那样,则请你补充说明.