令x为主元
6x?-7xy-3y?-xz+7yz-2z?
=6x?-(7y+z)x-3y?+7yz-2z?
=6x?-(7y+z)x+(z-3y)(y-2z)
3 (y-2z)
2 (z-3y)
2(z-3y)+3(y-2z)=7y+z
所以原式=（3x+y-2z)(2x-3y+z)
希望能解决您的问题.