($x – 2$)$3$ + ($3x – 1$)($3x + 1$) =($x + 1$)$3$
⇔$3x - 6$ + $9x^{2}$ - $3x + 3x - 1$ = $3x + 3$
⇔$3x - 7$ + $9x^{2}$ =$3x + 3$
⇔$3x - 7$ + $9x^{2}$ - $3x - 3$=$0$
⇔$-10$ + $9x^{2}$ = $0$
⇔ $9x^{2}$ = $10$
⇔ $x^{2}$ = $\frac{10}{9}$
⇔ $x ≈ 1,05$
Vậy $x ≈ 1,05$