\(\sqrt{x+1}-4x^2=\sqrt{3x}-1\left(x\ge0\right)\left(1\right)\)
\(\Leftrightarrow-4x^2+1+\sqrt{x+1}-\dfrac{\sqrt{6}}{2}=\sqrt{3x}-\dfrac{\sqrt{6}}{2}\)
\(\Leftrightarrow-\left(2x-1\right)\left(2x+1\right)+\dfrac{x+1-\dfrac{3}{2}}{\sqrt{x+1}+\dfrac{\sqrt{6}}{2}}=\dfrac{3x-\dfrac{3}{2}}{\sqrt{3x}+\dfrac{\sqrt{6}}{2}}\)
\(\Leftrightarrow-4\left(x-\dfrac{1}{2}\right)\left(x+\dfrac{1}{2}\right)+\dfrac{x-\dfrac{1}{2}}{\sqrt{x+1}+\dfrac{\sqrt{6}}{2}}-\dfrac{3\left(x-\dfrac{1}{2}\right)}{\sqrt{3x}+\dfrac{\sqrt{6}}{2}}=0\)
\(\Leftrightarrow\left(x-\dfrac{1}{2}\right)\left[-4\left(x+\dfrac{1}{2}\right)+\dfrac{1}{\sqrt{x+1}+\dfrac{\sqrt{6}}{2}}-\dfrac{3}{\sqrt{3x}+\dfrac{\sqrt{6}}{2}}\right]=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{2}\left(tm\right)\\-4\left(x+\dfrac{1}{2}\right)+\dfrac{1}{\sqrt{x+1}+\dfrac{\sqrt{6}}{2}}-\dfrac{3}{\sqrt{3x}+\dfrac{\sqrt{6}}{2}}=0\left(2\right)\end{matrix}\right.\)
\(\left(x\ge0\right)\Rightarrow\left(2\right)< 0\Rightarrow\left(2\right)vô\) \(nghiệm\)
\(\Rightarrow S=\left\{\dfrac{1}{2}\right\}\)
\(\)
