Giúp mình 3 bài với ạ. Mink cảm ơn

Bài `1`:

`a) 4x^3 -12x^2 y + 20x^3 y^2`

`=4 . x . x^2 - 4 . x^2 .3 y + 4. x^2 . 5 . x . y^2`

`= 4x^2 . ( x-3y + 5xy^2)`

`b) 3. (2x-3)^2 - 5. (2x-3)`

`= (2x-3). [3 .(2x-3) -5]`

`= (2x-3) . ( 6x - 9 - 5)`

`= (2x-3) . ( 6x - 14)`

`= (2x-3) . 2. (3x -7)`

`= 2. (3x-7) . (2x-3)`

`c) 4m^2 . (x+2) -2m .(x+2) +x+2`

`= (x+2) . (4m^2 - 2m +1)`

Bài `2`:

`a) 27m^3 -8`

`= (3m)^3 - 2^3`

`= (3m-2) [ (3m)^2 - 3m .2 + 2^2]`

`= (3m-2) . (9m^2+6m +4)`

`b) 9x^2 + 25 - 30x`

`= 9x^2 - 30x + 25`

`=(3x)^2 - 2 .3x . 5 + 5^2`

`= (3x-5)^2`

`c) 8x^3 - 36x^2 + 54x - 27`

`= (2x)^3 - 3. (2x)^2 . 3 + 3 . 2x . 3^2 - 3^3` 

`= (2x-3)^3`.

Bài `3`:

`a) 3x^3 - 2x =0`

`<=> x . (3x^2 -2)=0`

`<=> x =0` hoặc `3x^2 =2`

`<=> x =0` hoặc `x^2 =2/3`

`<=> x =0` hoặc `x  =+-(\sqrt(6))/3`

Vậy...

`b) 5. (3x-2)^2 -4. (3x-2)=0`

`<=> (3x-2) . [( 5. (3x-2) -4]=0`

`<=> (3x-2). ( 15x - 10 -4)=0`

`<=> (3x-2) . (15x - 14)=0`

`<=> 3x -2=0` hoặc `15x -14=0`

`<=> x= 2/3` hoặc `x = 14/15`

Vậy...

`c) x^2 -9=0`

`<=> (x-3) . (x+3)=0`

`<=> x-3=0` hoặc `x+3=0`

`<=> x=3` hoặc `x=-3`

Vậy...