a/ $\sqrt{3x^2}-\sqrt{12}=0$
⇔ $\sqrt{3}.x=\sqrt{12}$
⇔ $x=\frac{\sqrt{12}}{\sqrt{3}}$
⇔ $x=\sqrt{\frac{12}{3}}$
⇔ $x=\sqrt{4}$
⇔ $x=2$
b/ $\sqrt{\frac{x^2}{5}}-\sqrt{20}=0$
⇔ $\frac{\sqrt{x^2}}{\sqrt{5}}=\sqrt{20}$
⇔ $\frac{x}{\sqrt{5}}=\sqrt{20}$
⇔ $x=\sqrt{20}.\sqrt{5}$
⇔ $x=\sqrt{20.5}$
⇔ $x=\sqrt{100}$
⇔ $x=10$
Chúc bạn học tốt !!!
