Bài làm :
`(3x+2)(x^2−1)=(9x^2−4)(x+1)`
`⇔(3x+2)(x^2−1)−(3x−2)(3x+2)(x+1)=0`
`⇔(3x+2)[x^2−1−(3x^2+3x−2x−2)]=0`
`⇔(3x+2)(x^2−1−3x^2−3x+2x+2)=0`
`⇔(3x+2)(−2x^2+2x−x+1)=0`
`⇔(3x+2)[−2x(x−1)−(x−1)]=0`
`⇔(3x+2)[(x−1)(−2x−1)]=0`
`⇔` \(\left[ \begin{array}{l}3x+2=0\\x-1=0\\-2x-1=0\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}x=\dfrac{-2}{3}\\x=1\\x=\dfrac{-1}{2}\end{array} \right.\)
`\text{Vậy phương trình có tập nghiệm}` `S = { (-2)/3 ; 1 ; (-1)/2 }`
