\(a,3x-15xy=3x\left(1-5y\right)\\ ---\\ 8x^2+6x-4=2\left(4x^2+3x-2\right)\\ ---\\ 5x^2+25xy+10y^2=5\left(x^2+5xy+2y^2\right)\\ ---\\ 9x^2y^2+6x^2y-\dfrac{1}{2}xy^2=\dfrac{1}{2}xy\left(18xy+12x-y\right)\)

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)

\(1,=x\left(x^2-2x+1-y^2\right)=x\left[\left(x-1\right)^2-y^2\right]=x\left(x-y-1\right)\left(x+y-1\right)\\ 2,=\left(x+y\right)^3\\ 3,=\left(2y-z\right)\left(4x+7y\right)\\ 4,=\left(x+2\right)^2\\ 5,Sửa:x\left(x-2\right)-x+2=0\\ \Leftrightarrow\left(x-2\right)\left(x-1\right)=0\Leftrightarrow\left[{}\begin{matrix}x=1\\x=2\end{matrix}\right.\)

3x³ + 6x²y+ 3xy²

=3x³ + 3x²y + 3x²y + 3xy²

= 3x²(x +y) + 3xy(x +y)

=(x+y)(3x² + 3xy)

= 3x(x+y)(x+y)

= 3x(x+y)²

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

^2 + 4xy - 16 + 4y^2 
= x^2 + 4xy + 4y^2 - 4^2 
= (x + 2y)^2 - 4^2 
= (x + 2y - 4)(x + 2y + 4) 
2x^2-5xy-3y^2 
= 2^x + xy - 6xy - 3y^2 
= x(2x + y) - 3y(2x + y) 
= (2x + y)(x - 3y)

mình chưa hiểu

a: \(12x^3-6x^2+3x\)

\(=3x\cdot4x^2-3x\cdot2x+3x\cdot1\)

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

b: \(\dfrac{2}{5}x^2+5x^3+x^2y\)

\(=x^2\cdot\dfrac{2}{5}+x^2\cdot5x+x^2\cdot y\)

\(=x^2\left(\dfrac{2}{5}+5x+y\right)\)

c: \(14x^2y-21xy^2+28x^2y^2\)

\(=7xy\cdot2x-7xy\cdot3y+7xy\cdot4xy\)

\(=7xy\left(2x-3y+4xy\right)\)