\(=x\left(x+2y\right)-\left(x+2y\right)=\left(x+2y\right)\left(x-1\right)\)

a) xy+3x-7y-21

=x(y+3)-7(x+3)

=(x-7)(y+3)

b)2xy-15-6x-5y

=2x(y-3)-5(-3+y)

=(2x-5)(y-3)

c)2x^2y+2xy^2-2x-2y

=2x(xy-1)+2y(xy-1)

=(2x+2y)(xy-1)

x(x+3)-5x(x-5)-5(x+3)

=(x-5)(x+3)-5x(x-5)

=(x-5)(x+3-5x)

Câu cuối mình bị nhầm dòng cuối phải là (x-5)(x+3+x-5)=(x-5)(2x-2)nha bạn

a) xy+3x-7y-21=(xy+3x)-(7y+21)= x(y+3)-7(y+3)=(y+3)(x-7)

b)2xy-15-6x+5y=(2xy-6x)+(5y-15)=2x(y-3)+5(y-3)=(y-3)(2x+5)

c)2x^2y+2xy^2-2x-2y=2xy(x+y)-2(x+y)=2(x+y)(xy-1)

d) x(x+3)-5x(x-5)-5(x+3)=[x(x+3)-5(x+3)]-5x(x-5)=(x+3)(x-5)-5x(x-5)=(x-5)(x+3-5x)=(x-5)(3-4x)

`a^3-a^2 x -ay+xy`

`=a^2(a-x)-y(a-x)`

`=(a-x)(x^2-y)`

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

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

`=x(x+1)-2y(x+1)`

`=(x+1)(x-2y)`

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

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

`=x(x-2)-y(x-2)`

`=(x-2)(x-y)`

1,(a^2-y)(a-x)

2,(x+1)(x-2y)

\(x^2y-2xy^2+y^3=y\left(x^2-2xy+y^2\right)=y\left(x-y\right)^2\)

\(=y\left(x^2-2xy+y^2\right)=y\left(x-y\right)^2\)

\(x^2y-2xy^2+y^3=y\left(x^2-2xy+y^2\right)=y\left(x-y\right)^2\)

1) \(\left(3x+2\right)^2-\left(x-6\right)^2=\left(3x+2-x+6\right)\left(3x+2+x-6\right)=\left(2x+8\right)\left(4x-4\right)=8\left(x+4\right)\left(x-1\right)\)

2) \(A=x^2+2y^2+2xy-2y+2021=\left(x^2+2xy+y^2\right)+\left(y^2-2y+1\right)+2020=\left(x+y\right)^2+\left(y-1\right)^2+2020\ge2020\)

\(minA=2020\Leftrightarrow\)\(\left\{{}\begin{matrix}x=-1\\y=1\end{matrix}\right.\)

\(\left(3x+2\right)^2-\left(x-6\right)^2=\left(3x+2-x+6\right)\left(3x+2+x-6\right)=\left(2x+8\right)\left(4x-4\right)=2.\left(x+4\right).4\left(x-1\right)=8\left(x-1\right)\left(x+4\right)\)

Bài 1: 

Ta có: \(\left(3x+2\right)^2-\left(x-6\right)^2\)

\(=\left(3x+2-x+6\right)\left(3x+2+x-6\right)\)

\(=\left(2x+8\right)\left(4x-4\right)\)

\(=8\left(x+4\right)\left(x-1\right)\)

\(=y\left(1-x^2-2xy-y^2\right)=y\left[1-\left(x+y\right)^2\right]=y\left(1-x-y\right)\left(1+y+x\right)\)

a) \(2xy-y+6x-3=\left(2xy+6x\right)-\left(y+3\right)=2x\left(y+3\right)-\left(y+3\right)=\left(2x-1\right)\left(y+3\right)\)

b) \(x^2-2xy-x+2y=\left(x^2-2xy\right)-\left(x-2y\right)=x\left(x-2y\right)-\left(x-2y\right)=\left(x-1\right)\left(x-2y\right)\)

x^2 + 2y^2 - 2y - 2xy + 1  = (x^2 - 2xy + y^2) + (y^2 - 2y + 1) = (x - y)^2 + (y - 1)^2

\(x^2+2y^2-2y-2xy+1\)

\(=x^2-2xy+y^2+y^2-2y+1\)

\(=\left(x-y\right)^2+\left(y-1\right)^2\)

\(=\left(x-y\right)^2-\left(1-y\right)^2\)

\(=\left(x-y-1+y\right)\left(x-y+1-y\right)\)

\(=\left(x-1\right)\left(x-2y+1\right)\)

\(x^3-8y^3-2xy\left(x-2y\right)=\left(x-2y\right)\left(x^2+2xy+4y^2\right)-2xy\left(x-2y\right)\)

\(=\left(x-2y\right)\left(x^2+2xy+4y^2-2xy\right)=\left(x-2y\right)\left(x^2+4y^2\right)\)

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

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

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