1、(a-b)/a(a+b) ×a²(a+b)(a-b)/[-a(a-b)]=-(a-b)=b-a2、x(x-3)/(x-3)²×(x-5)(x-6)/x(x-5)=(x-6)/(x-3)3、-(x+4)(x-4)/(x-3)(x+1)×(x-3)/(x-1)(x-4)=-(x+4)/(x+1)(x-1)=(x+4)/(1-x²)