<=> ($x^{3}$ + 1)$^{2}$ = 3x +1
<=> x^6 + 2x^3 +1 = 3x + 1
<=> x^6 + 2x^3 - 3x = 0
<=> x^6 + 3x^3 - x^3 - 3x =0
<=> x^4(x^2+3) - x(x^2 + 3) =0
<=> (x^4-x)(x^2+3)=0
<=> \(\left[ \begin{array}{l}x^4 - x = 0\\x^2 + 3 =0\end{array} \right.\)
<=> \(\left[ \begin{array}{l}x^3 - 1 = 0\\x^2 = -3 (vô lí)\end{array} \right.\)
<=> \(\left[ \begin{array}{l}x=1\\x=-1\end{array} \right.\)
Hoặc x = 0