x^2-y^2-z^2-2yz-2x+1
=x^2-2x+1-(y^2+z^2+2yz)
=(x-1)^2-(y+z)^2
=[(x-1)+(y+z)][(x-1)-(y+z)]
=(x+y+z-1)(x-y-z-1)
分解因式：X方-Y方-Z方-2YZ-2X+1(X方就是X的平方）
x^2-y^2-z^2-2yz-2x+1
=x^2-2x+1-(y^2+z^2+2yz)
=(x-1)^2-(y+z)^2
=[(x-1)+(y+z)][(x-1)-(y+z)]
=(x+y+z-1)(x-y-z-1)