do may minh khong viet dk tieng viet nen ban thong cam nha
minh thay he nay la he doi xung
nen lay 2 pt tru cho nhau ta duoc
\sqrt{3+x\tfrac{2}{1}} +3\sqrt{x+3}=\sqrt{3+x^{2}} + 3\sqrt{y+3}
sau do dung ham so ta dk x=y
thay vao [t 1 ta thay X= 1 la pt
mong la dung