(!)3x^3-12x^2y+12xy^2
=3x(x^2-4xy+4y^2)
=3x(x-2y)^2
(平方不好写用^代替）
(2)4/9-0.01y^2
=(2/3)^2-(0.1y)^2
=(2/3+0.1y)(2/3-0.1y)
帮你解答天冷死了.