a) 3xy2 - 3x3 - 6xy + 3x
=3x (y2 - x2 - 2y +1)
= 3x [ (y-1)2 -x2 ]
=3x (y-1-x)(y-1+x)
b) 3x2 +11x+6
= 3 x2 +9x +2x +6
=3x (x+3)+2(x+3)
= (x+3)(3x+2)
c) -x3 - 4xy2 + 4x2y +16x
= -x (x2 + 4y2 - 4xy -16 )
= -x [(x -2y)2 - 42 ]
= -x(x-2y-4)(x-2y+4)
d) xz - x2 -yz +2xy -y2
= (xz-yz) -(x2-2xy+y2 )
= z(x-y) - (x-y)2
= (x-y)(z-(x-y))
= (x-y)(z-x+y)
e) 4x2 - y2 - 6x + 3y
= [(2x)2 - y2 ]- 3(2x - y)
= (2x-y)(2x+y) - 3(2x-y)
=(2x-y)(2x+y-3)