(1)3x^2+6xy =3x(x+2y)
(2)2x(x-y)+x^2(y-x)=x(x-y)(2-x)
(3)题目是否有问题,应该为：x^3y-2x^2y^2+xy^3,如果是,解答如下
x^3y-2x^2y^2+xy^3=xy(x^2-2xy+y^2)=xy(x-y)^2
(4)4a^2+16b^2+8ab=4(a^2+4ab+4b^2)=4(a+2b)^2