1.原式=
-cda^2+(bc^2-bd^2)a+b^2cd
=(bc-ad)(ac+bd)
2.原式=
2(x^2+2xy+y^2-4z^2)
=2[(x+y)^2-(2z)^2]
=2(x+y+2z)(x+y-2z)
3.原式=x^3+x^2-4(x^2-1)
=x^2(x+1)-4(x+1)(x-1)
=(x+1)(x^2-4x+4)
=(x+1)(x-2)^2
4.原式=(x^3-1)^2-(y^3)^2
=(x^3+y^3-1)(x^3-y^3-1)
如果楼主还有什么不懂的话尽管问我