（x-y)³-x+y
=（x-y）[(x-y)²-1]
=(x-y)(x-y+1)(x-y-1)
（a+b）²-（a-b）²
=(a+b+a-b)(a+b-a+b)
=2a*2b
=4ab
(x-3)³-4x+12
=(x-3)³-4(x-3)
=(x-3)[(x-3)²-1]
=(x-3)(x-3+1)(x-3-1)
=(x-3)(x-2)(x-4)
如果本题有什么不明白可以追问,