ĐKXĐ: ....
\(\Leftrightarrow2x=\left(x+1\right)\sqrt{3x+1}+x+1\)
\(\Leftrightarrow\left(x+1\right)\sqrt{3x+1}-x+1=0\)
Đặt \(\sqrt{3x+1}=a\ge0\Rightarrow x=\frac{a^2-1}{3}\)
\(\left(\frac{a^2-1}{3}+1\right)a-\frac{a^2-1}{3}+1=0\)
\(\Leftrightarrow a^3-a^2+2a+4=0\)
\(\Leftrightarrow\left(a+1\right)\left(a^2+2a+4\right)=0\)
\(\Rightarrow a=-1\left(l\right)\)
Vậy pt vô nghiệm