a (3-2x)2 = 6 - 4x

b (xy+5)2 = 2xy + 10

c (2x+1)(1-2x) = 2x - 4x² + 1 - 2x = 4x2 + 1

d (1-5x)3 = 3-15x

e (2x+y)(4x2 - 4xy + y2) = 8x³ -8x²y+2xy² + 4x²y-4xy² + y³ = 8x³ + y³ - 4x²y - 2xy²

cảm ơn bạn nha

`a, (3x+4)^2 = 9x^2 + 24x + 16`

`b, (5x-y)^2 = 25x^2 - 10xy + y^2`

`c, (xy - 1/2y)^2 = x^2y^2 - xy^2 + 1/4y^2`

a) \(\dfrac{x^2-2x+1-x^2-2x-1+4}{\left(x+1\right)\left(x-1\right)}=\dfrac{-4\left(x-1\right)}{\left(x+1\right)\left(x-1\right)}=\dfrac{-4}{x+1}\)

\(\dfrac{xy\left(x^2+y^2\right)}{xy\left(x^3\right)}.\dfrac{1}{x^2+y^2}=\dfrac{1}{x^3}\)

a: =1/2x^3*x^2-1/2x^3*6x-1/2x^3*10

=1/2x^5-3x^4-5x^3

b: =-3x^2*5x^3+3x^2*4x^2-3x^2*3x+3x^2*3x

=-15x^5+12x^4-9x^3+9x^2

c: \(=3x\cdot5x^2-3x\cdot2x-3x=15x^3-6x^2-3x\)

d: \(=\dfrac{1}{2}x^2y\cdot2x^3-\dfrac{1}{2}x^2y\cdot\dfrac{2}{5}xy^2-\dfrac{1}{2}x^2y=x^5y-\dfrac{1}{5}x^3y^3-\dfrac{1}{2}x^2y\)

`a, (3x+1)^2 = 9x^2 + 6x + 1`.

`b, (4x+5y)^2 = 16x^2 + 20xy + 25y^2`

`c, (5x-1/2)^2 = 25x^2 - 5x + 1/4`

`d, (-x+2y^2)^2 = x^2 - 2y^2x + 4y^4`.

`a)`

`(3x + 1)^2`

`= 9x^2 + 6x + 1`

`b)`

`(4x + 5y)^2`

`= 16x^2 + 40xy + 25y^2`

`c)`

`(5x - 1/2)^2`

`= 25x^2 - 5x + 1/4`

`d)`

`(-x + 2y^2)^2`

`= x^2 - 4xy^2 + 4y^4`

\(a,=4x^2+12xy+9y^2\\ b,=25x^2-10xy+y^2\\ d,=4x^2+4xy^2+y^4\\ e,=9x^4-12x^2y+4y^2\\ g,=x^3+64\)

a) x-y

b) 8x²+x

c) 1

Bài 5:

a: \(x^3-1-\left(x^2+2x\right)\left(x-2\right)=5\)

=>\(x^3-1-\left(x^3-2x^2+2x^2-4\right)=5\)

=>\(x^3-1-x^3+4=5\)

=>3=5(vô lý)

b: \(\left(x+1\right)^3-\left(x-1\right)^3-6\left(x-1\right)^2=-10\)

=>\(x^3+3x^2+3x+1-\left(x^3-3x^2+3x-1\right)-6\left(x^2-2x+1\right)=-10\)

=>\(x^3+3x^2+3x+1-x^3+3x^2-3x+1-6x^2+12x-6=-10\)

=>12x-4=-10

=>12x=-6

=>x=-6/12=-1/2

BÀi 3:

a: \(A=\left(a+b\right)^3-\left(a-b\right)^3\)

\(=a^3+3a^2b+3ab^2+b^3-\left(a^3-3a^2b+3ab^2-b^3\right)\)

\(=a^3+3a^2b+3ab^2+b^3-a^3+3a^2b-3ab^2+b^3=6a^2b+2b^3\)

b:Sửa đề: \(A=\left(u-v\right)^3+3uv\left(u-v\right)\)

\(=u^3-3u^2v+3uv^2-v^3+3u^2v-3uv^2=u^3-v^3\)

c: \(C=6\left(c-d\right)\left(c+d\right)+2\left(c-d\right)^2-\left(c-d\right)^3\)

\(=6\left(c^2-d^2\right)+2\left(c^2-2cd+d^2\right)-c^3+3c^2d-3cd^2+d^3\)

\(=6c^2-6d^2+2c^2-4cd+2d_{}^2-c^3+3c^2d-3cd^2+d^3\)

\(=-c^3+3c^2d-3cd^2+d^3+8c^2-4cd-4d^2\)

Bài 2:

a: \(x^3+3x^2+3x+1=x^3+3\cdot x^2\cdot1+3\cdot x\cdot1^2+1^3=\left(x+1\right)^3\)

b: \(m^3+9m^2n+27mn^2+27n^3\)

\(=m^3+3\cdot m^2\cdot3n+3\cdot m\cdot\left(3n\right)^2+\left(3n\right)^3\)

\(=\left(m+3n\right)^3\)

a. (3a + 1)³

= 27a³ + 27a² + 9a + 1