Giải phương trình: 6x^3-11x^2-19x-6=0

`6x^3 -11x^2 -19x -6 =0`

`<=> 6x^3 -18x^2 + 7x^2 -21x +2x -6=0`

`<=>6x^2(x -3) +7x(x -3) +2(x-3)=0`

`<=> (6x^2 +7x +2)(x-3)=0`

`<=> (6x^2 +4x +3x +2)(x-3)=0`

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

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

`<=>` \(\left[ \begin{array}{l}2x +1=0\\3x+2=0\\x-3=0\end{array} \right.\) 

`<=>` \(\left[ \begin{array}{l}x = -\dfrac{1}2\\x = -\dfrac{2}3\\x=3\end{array} \right.\)

Vậy `S={-1/2 ; -2/3 ; 3}`