$2^{}\sqrt[]{20x+4}+3\sqrt[]{45x+9}=52$ (ĐKXĐ : $x^{}$ $\geq$ $\dfrac{-1}{5}$ )
⇔ $2^{}\sqrt[]{4(5x+1)}+3\sqrt[]{9(5x+1)}=52$
⇔ $2.2^{}\sqrt[]{5x+1}+3.3\sqrt[]{5x+1}=52$
⇔ $4\sqrt[]{5x+1}+9\sqrt[]{5x+1}=52$
⇔ $13^{}\sqrt[]{5x+1}=52$
⇔ $\sqrt[]{5x+1}=4$
⇔ $5x^{}+1=16$
⇔ $5x^{}=15$
⇔ $x^{}=3(TM)$
Chúc bạn học tốt !!!!!!