Đáp án+Giải thích các bước giải:
`a)`
`3x^3-4x^2-3x+4=0`
`⇔(3x^3-4x^2)+(-3x+4)=0`
`⇔x^2(3x-4)-1(3x-4)=0`
`⇔(x^2-1)(3x-4)=0`
`⇔(x-1)(x+1)(3x-4)=0`
\(⇔\left[ \begin{array}{l}x-1=0\\x+1=0\\3x-4=0\end{array} \right.\)
\(⇔\left[ \begin{array}{l}x=1\\x=-1\\x=\dfrac{4}{3}\end{array} \right.\)
Vậy `x=1` hoặc `x=-1` hoặc `x=4/3`
`b)`
`x^3-x-6=0`
`⇔x^3-2x^2+2x^2-4x+3x-6=0`
`⇔x^2(x-2)+2x(x-2)+3(x-2)=0`
`⇔(x-2)(x^2+2x+3)=0`
TH 1:
`x-2=0`
`⇔x=2`
TH 2:
`x^2+2x+3=0`
`⇔x^2+2x+1+2=0`
`⇔(x+1)^2+2=0`
`⇔(x+1)^2=-2` (Vô lí)
Vậy `x=2`
