1、x^2y-6xy^2+9y^2

1、x^2y-6xy^2+9y^2
=y(x²-6xy+9y)
2、（y^2+4）^2-16y^2
=(y²+4-4y)(y+4+4y)
=(y-2)²(y+2)²
3、(a-b)m^2+(b-a)n^2
=(a-b)m²-(a-b)n²
=(a-b)(m²-n²)
=(a-b)(m+n)(m-n)
4、x^3-2x[2分之1x^2-3)(6分之1x-1)-4分之1x]
看不太清楚
5、(a+1)^2-(1-a)(-a-1)
=(a+1)²-(a-1)(a+1)
=(a+1)(a+1-a+1)
=2(a+1)
6、[(2xy+3)(2xy-3)+（xy+3^2）]÷xy
=(4x²y²-9+xy+9)÷xy
=(4x²y²+xy)÷xy
=4xy+1

因式分解吗？好乱！