1、12a³b²-9a²b+3ab =3ab(4a²b-3a+1)
2、a³-4a²b+4ab² =a(a² -4ab+4b²)=a(a-2b)²
3、(3x+y)²-(x-3y)²=（3x+y+x-3y)(3x+y-x+3y)=(4x-2y)(2x+4y)=4(2x-y)(x+2y)
4、(2a-b)²+8ab =4a ² -4ab+b²+8ab=4a²+4ab+b²=(2a+b)²