x立方-4x+3x平方-12
=x²(x+3)-4(x+3)
=(x+3)(x²-4)
=(x+3)(x+2)(x-2)
4x平方-4xy+4x-2y+y平方
=(2x-y)²+2(2x-y)
=(2x-y)(2x-y+2)