1)
a)(2x-y)(4x^2-2xy+y^2)
=(2x-y)[(2x)^2+(2x).y+y^2-8xy]
=8x^3-y^3 -8xy(2x-y)
=8x^3-y^3-8x^2 y +8xy^2
b)
(2x^3-21x^2+67x+60)/(x-5)
x≠5
=[2x^2(x-5)-11x(x-5)+12x(x-5)]/(x-5)
=2x^2-11x+12

1)
a) (2x-y)(4x^2-2xy+y^2)
=(2x-y)[(2x)^2+(2x).y+y^2-4xy]
=8x^3-y^3 -4xy(2x-y)
=8x^3-y^3-8x^2 y +4xy^2

câu 2
A = (3x - 5)(2x + 11) - (2x + 3)(3x + 7)
= 6x^2 - 10x + 33x - 55 - (6x^2 + 9x + 14x + 21)
= 6x^2 + 23x - 55 - 6x^2 - 23x - 21
= -76
B = (2x + 3)(4x^2 - 6x + 9) - 2.(4x^3 - 1)
= (2x + 3)((2x)^2 - (2x).3 + 3^2) - 2.(4x^3 - 1)
= 8x^3 + 27 - 8x^3 + 2
= 29
vậy các biểu thức trên đều ko phụ thuộc vào x

3)
a.
x^2-y^2-2x+2y
(x-y)(x+y)-2(x-y)
=(x-y)[(x+y)-2]
=(x-y)(x+y-2)
b)
2x+2y-x^2-xy
2(x+y)-x(x+y)
(x+y)(2-x)

câu 3
a.
x^2 - y^2 - 2x + 2y
= (x - y)(x + y) - 2(x - y)
= (x - y)(x + y - 2)
b.
2x + 2y - x^2 - xy
= x(2 - x) + y(2 - x)
= (2 - x)(x + y)
c.
3a^2 - 6ab + 3b^2 - 12c^2
= 3(a - b)^2 - 3.(2c)^2
= 3.(a - b - 2c)(a - b + 2c)

d.
a^2 + 2ab + b^2 - ac - bc
= (a + b)^2 - c(a + b)
= (a + b)( a + b - c)
e.
x^2 - 2x - 4y^2 - 4y
= (x^2 - 2x + 1) - (4y^2 + 4y + 1)
= (x - 1)^2 - (2y - 1)^2
= (x - 1 - 2y + 1)(x - 1 + 2y - 1)
= (x - 2y)(x + 2y - 2)
g.
x^2y - x^3 - 9y + 9x
= x^2.(y - x) - 9(y - x)
= (x^2 - 9)(y - x)
= (x - 3)(x + 3)(y - x)