b) $\sqrt{4x - 8}$ - 12$\sqrt{\frac{x - 2}{9}}$ = -1 Đkxđ: x ≥ 2
⇔ $\sqrt{4.(x - 2}$ - 12.$\sqrt{(x - 2).\frac{1}{9}}$ = -1
⇔ 2$\sqrt{x - 2}$ - 12.$\frac{1}{3}$.$\sqrt{x - 2}$ = -1
⇔ $\sqrt{x - 2}$.(2 - 4) = -1
⇔ -2$\sqrt{x - 2}$ = -1
⇔ $\sqrt{x - 2}$ = $\frac{1}{2}$
⇔ x - 2 = $\frac{1}{4}$
⇔ x = $\frac{9}{4}$ (t/m)
Vậy x = $\frac{9}{4}$
