a, x6 - x4 + 2x3 + 2x
= x(x5- x3 + 2x2 + 2)
b, x2 + 2x + 1 - y2
= (x + 1)2 - y2
= (x + 1 + y)(x + 1 - y)
c, x2 + 2xy + y2 - 9z2
= (x + y)2 - 9z2
= (x + y + 3z)(x + y - 3z)s
d, x3 - 10x2 + 25x - 16xy2
= x(x2 - 10x + 25 - 16y2)
= x[(x - 5)2 - 16y2]
= x(x - 5 - 4y)(x - 5 + 4y)
e, 3xy2 - 2xy + 12x
= x(3y2 - 2y + 12)