`(x-1)^{2}=x-1`

`<=>(x-1)^{2}-(x-1)=0`

`<=>(x-1)(x-1-1)=0`

`=>x-1=0` hoặ `x-2=0`

`<=>x=1` hoặc `x=2`

\(5x\left(x-2\right)-\left(2-x\right)=0\)

\(\Leftrightarrow5x\left(x-2\right)+\left(x-2\right)=0\)

\(\Leftrightarrow\left(x-2\right)\left(5x+1\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=2\\x=-\dfrac{1}{5}\end{matrix}\right.\)

`5x(x-2)-(2-x)=0`

`<=>5x(x-2)+(x-2)=0`

`<=>(x-2)(5x+1)=0`

`=>x-2=0` hoặc `5x+1=0`

`<=>x=2` hoặc `x=-1/5`

`12x^2 - 4x =4x(3x-1)`.

`->` Đúng

sai

Ta có :

 \(VT=x\left(y-1\right)+3\left(y-1\right)=\left(y-1\right)\left(x+3\right)\)

\(VP=-\left(1-y\right)\left(x+3\right)=\left(y-1\right)\left(x+3\right)\)

\(\Rightarrow VT=VP\)

Vậy đẳng thức trên đúng

(x+3) y-x+3=(4x+9)y-4x-9

-(4x+9) y+(x+3) y-x-(-4x)+12=0

-3((x-2) y-x-4)=0

(x+2) y-x-4=0

x+2=0

x=-2

y-1=0

y=1

\(14x^2y-21xy^2+28x^2y^2\\ =7xy\left(2x-3y+4xy\right)\)

`14x^2y - 21xy^2 + 28x^2y^2`

`= 7xy(2x-3y+4xy)`.

`3x-12x^{2}`

`=3x.1-3x.4x`

`=3x.(1-4x)`

Lời giải:

$3x-12x^2=3x(1-4x)$

Đề thiếu. Bạn xem lại.

   (2x³ - 3x - 1).(5x +2)

= 10x⁴ +  4x³ - 15x² - 6x - 5x - 2

= 10x⁴ + 4x³ - 15x² - 11x - 2

   (2x3 - 3x - 1).(5x +2)

= 10x4 +  4x3 - 15x2 - 6x - 5x - 2

= 10x4 + 4x3 - 15x2 - 11x - 2