x^2-y^2+x^3-y^3
=(x+y)(x-y)+(x-y)(x^2+xy+y^2)
=(x+y)(x^2+xy+y^2+x+y)
x^2-y^2-z^2-2yz-2x+1
=(x^2-2x+1)-(y^2+2yz+z^2)
=(x-1)^2-(y+z)^2
=(x-1+y+z)(x-1-y-z)