1　　x^2+x^2y-6y^2-5y-1
=x^2(1+y)- 这里的符号写错了吧?
2 x^2-2y^2-2z^2-xy+5yz-xz
=x^2-(y+z)x-(2y^2-5yz+2z^2)
=x^2-（y+z)x-(2y-z)(y-2z)
=(x+2y-z)(x+y-2z)不好意思啊，是x^4+x^2y-6y^2-5y-1x^4+x^2y-6y^2-5y-1=(x^2）^2+yx^2-(6y^2+5y+1)=(x^2）^2+yx^2-(3y+1)(2y+1)=(x^2+3y+1)(x^2-2y-1)