Question

tìm x 

3x^2(2x+1)-6x(1+2x)=0 

Answer 1

=>3x(2x+1)(x-2)=0

=>x=0; x=-1/2;x=2

Answer 2

`3x^2(2x+1)-6x(1+2x)=0 `

`<=> (3x^2 -6x ) (2x+1) =0`

`<=> 3x(x-2)(2x+1) =0`

`@TH1 : 3x =0 => x=0`

`@TH2 : x-2 =0 => x =2`

`@TH3 : 2x+1 =0 => 2x=-1 => x =-1/2`

Vậy `S={0;2;-1/2}`