分式分解.
(1).1/(x-y)-1/x+y
(2).(1-x)/(x-2)+2=1/x-2
(3.)1/(x^2-2x)-1/(x^2-4x+4)
(4.)[a^2-5a+2/(a+2)+1]*(a^2+4a+4)/a^2-4
2.(1-x)/(x-2)的商+2=1除以x-2
4.(a^2-5a+2)除以a+2再+1..的和乘a^2+4a+4除a^2-4
帮写点过程出来。