Bài 1:
a) 3x^2 - 6x + 9x^3 = 3x^2(3x - 2)(x + 1)
b) 2x + 2y - x^2 - xy = -(x - 2)(x + y - 2)
c) x^2 - 2x - 4y^2 - 4y = (x - 2 - 2y)(x + 2y + 2)
d) x^2 y - x^3 - 9y + 9x = x(x - 3)(x^2 y + 9) - 9(y - x)
e) x^2 - 25 + y^2 + 2xy = (x + y - 5)(x + y + 5)
f) (x^2+1)^2 - 4x^2 = (x^2 - 2x + 1)(x^2 + 2x + 1)
g) x^2(x-1) + 16(1-x) = -(x - 4)(x^2 - x - 16)
h) 5x(x - 2y) + 2(2y - x)^2 = (x - 2y)(10x - 4y)

Bài 2:
a) x^2 - 6x - 16 = (x - 8)(x + 2)
b) x^3 - x^2 - 6x = x(x - 3)(x + 2)
c) 16x - 5x^2 - 3 = -(5x - 1)(x + 3)
d) x^4 + 5x^2 + 9 = (x^2 + 3)^2 + 2^2
e) (x^2 + 3x + 1)(x^2 +3x - 3) -5 = (x^2 + 3x - 4)(x^2 + 3x + 2)
f) (x+2)(x+4)(x+6)(x+8) + 7 = (x^2 + 10x + 16)(x^2 + 10x + 14) + 7
g) (x^2 + 9)^2 + 8x(x^2 + 9) + 12x^2 = (x^2 + 4x + 9)^2
h) (3x - 2)^2 (6x - 5)(6x - 3) - 5 = (9x^2 - 12x + 4)(36x^2 - 54x + 19) - 5

Bài 3:
a) x^4 - 1024 = (x^2 - 32)(x^2 + 32)
b) 81x^4 + 4y^4 = (9x^2 + 2y^2)(9x^2 - 2y^2)
c) x^3 - x^2 - 4 = (x - 2)(x^2 + x + 2)
d) x^3 - 5x^2 + 8x - 4 = (x - 1)^2(x - 4)
e) x^3 + 9x^2 + 23x +15 = (x + 3)(x + 5)(x + 1)
f) x^3 - 4x^2 + 12x - 27 = (x - 3)^2(x + 1)
g) x^4 + 6x^3 + 11x^2 + 6x + 1 = (x + 1)^2(x^2 + 4x + 1)
h) a^3(c - b^2) + b^3(a - c^2) + c^3(b - a^2) + abc(abc - 1) = (a + b + c)(a^2 + b^2 + c^2 - ab - ac - bc)(a - b)^2(b - c)^2(c - a)^2