Có (3x+2)(x^2+2) = (9x^2-4)(x+1)
=> (3x+2)(x^2+2) = (3x+2)(3x-2)(x+1)
=> (3x+2)(x^2+2) - (3x+2)(3x-2)(x+1) =0
=> (3x+2)(x^2+2) - (3x+2)(3x^2+x-2) = 0
=> (3x+2)( x^2 +2 - 3x^2 -x+ 2) = 0
=> (3x+2)(-2x^2 - x +4 ) = 0
=> (3x+2)( 2x^2 + x -4 ) = 0
=> 3x+2 = 0 ( vì 2x^2 +x-4 > 0 )
=> x = -2/3