Phân tích đa thức sau thành nhân tử

Bài 1:
a, 16x^2 - 8x + 1 - 3(4x - 1)
= 16x^2 - 8x + 1 - 12x + 3
= 16x^2 - 20x + 4
= 4(4x^2 - 5x + 1)
= 4(x - 1)(4x - 1)

b, 27x^3 + 8
= (3x)^3 + 2^3
= (3x + 2)(9x^2 - 6x + 4)

c, -16x^4y^6 - 24x^5y^5 - 9x^6y^4
= -x^4y^4(16y^2 + 24xy + 9x^2)
= -x^4y^4(4y + 3x)^2

d, (ax + by)^2 - (ay + bx)^2
= (ax + by + ay + bx)(ax + by - ay - bx)
= (a(x + y) + b(x + y))(a(x + y) - b(x + y))
= (a + b)(x + y)(a - b)(x + y)
= (a + b)(a - b)(x + y)^2

Bài 2:
a, (a^2 + b^2 - 5)^2 - 2(ab + 2)^2
= (a^2 + b^2 - 5 + √2(ab + 2))(a^2 + b^2 - 5 - √2(ab + 2))

b, (4a^2 - 3a - 18)^2 - (4a^2 + 3a)^2
= (4a^2 - 3a - 18 + 4a^2 + 3a)(4a^2 - 3a - 18 - 4a^2 - 3a)

c, -(x + 2) + 3(x^2 - 4)
= -x - 2 + 3x^2 - 12
= 3x^2 - x - 14

d, 125a^3 - 27b^3
= (5a)^3 - (3b)^3
= (5a - 3b)(25a^2 + 15ab + 9b^2)