đặt
[TEX]\begin{array}{l}\sqrt {{x^2} - x + 1} = u\left( {u \ge \frac{{\sqrt 3 }}{2}} \right);\sqrt {x - 2} = v\left( {v \ge 0} \right)\\pt \Leftrightarrow \left( {{u^2} - 5{v^2}} \right)u = 2\left( {{u^2} - 3{v^2}} \right)v\left( 1 \right)\\x = 2 \to ko - t/m\\x > 2 \to v > 0\\ \Rightarrow \left( 1 \right) \Leftrightarrow {t^3} - 2{t^2} - 5t + 6 = 0\\ \Leftrightarrow ......\end{array}[/TEX]