（1）2ab(a-2)-8b(a-1)(a-2) =2(a-2)(ab-4ab+4b) =2(a-2)(4b-3ab) =2b(a-2)(4-3a) (2)a(x-1)+b(x-1)-c(1-x) =a(x-1)+b(x-1)+c(x-1) =(x-1)(a+b+c)
