3x² - 3xy

= 3x ( x - y )

`3x^2 - 6x`

`= 3x.x-3x.2`

`=3x(x-2)`

`3x-3y+a(x-y)`

`=3(x-y)+a(x-y)`

`=(x-y)(a+3)`

\(3x-3y+a\left(x-y\right)=\left(x-y\right)\left(a+3\right)\)

bạn có thể ghi rõ lại được ko ạ, bạn có thể thay dấu nhân bằng dấu chấm

Ta có: \(3x\left(x-1\right)^2-5x^2\left(x-1\right)-7\left(x-1\right)\)

\(=\left(x-1\right)\left[3x\left(x-1\right)-5x^2-7\right]\)

\(=\left(x-1\right)\left(3x^2-3x-5x^2-7\right)\)

\(=\left(x-1\right)\left(-2x^2-3x-7\right)\)

\(=3x\cdot\left(x-5y\right)+2y\cdot\left(x-5y\right)\)

\(=\left(x-5y\right)\left(3x+2y\right)\)

\(3x\left(x-5y\right)-2y\left(5y-x\right)\)

\(=3x\left(x-5y\right)+2y\left(x-5y\right)\)

\(=\left(x-5y\right)\left(3x+2y\right)\)

\(3x\left(x-7\right)+2xy-14y\)

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

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

#\(Toru\)

\(14x^2-14xy-8x+8y=14x\left(x-y\right)-8\left(x-y\right)=\left(x-y\right)\left(14x-8\right)\)

\(14x^2-14xy-8x+8y\)

\(=14x\left(x-y\right)-8\left(x-y\right)\)

\(=\left(14x-8\right)\left(x-y\right)\)

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

\(14x^2-14xy-8y+8y=2\left(x-y\right)\left(7x-4\right)\)

= ( 7x² + 14xy + y² ) - 1

= ( 7x + y )² - 1

= [(7x + y) + 1] [( 7x + y) - 1]

49.x^2 - 1 + 14xy + y^2
= (49.x^2 + 14xy + y^2) - 1
= (7x + y)^2 - 1
= (7x + y + 1)(7x + y - 1)

(x-1)(3x-4x)

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