(a²+ab-ac)/(a²-ab)·[(a-b)²-c²]/(a²+2ab+b²)÷[a²-(b-c)²]/(b²-a²)
=a(a+b-c)/[a(a-b)]·(a-b-c)(a-b+c)/(a+b)²·(b-a)(b+a)/(a-b+c)(a+b-c)
=(b+c-a)/(a+b).=(-2-3-1)/-1=6
(a²+ab-ac)/(a²-ab)·[(a-b)²-c²]/(a²+2ab+b²)÷[a²-(b-c)²]/(b²-a²)
=a(a+b-c)/[a(a-b)]·(a-b-c)(a-b+c)/(a+b)²·(b-a)(b+a)/(a-b+c)(a+b-c)
=(b+c-a)/(a+b).=(-2-3-1)/-1=6