①把(3/a-1)+(2/2-a)通分,得(4-a)/(a-1)(2-a)
②(a＾2/a-b)-a-b=(a＾2/a-b)-(a+b),通分得b^2/(a-b)
③先把(1-2/x+1)通分,得(x-1)/(x+1),再＾2并÷(x-1/x+1),最后得(x-1)/(x+1).