\(4x^2-14x+5+\sqrt{3x+1}=0\)
\(\Leftrightarrow 4x^2-(13x-3x)+(5+1)=0\)
\(\Leftrightarrow 4x^2-10x+6=0\)
\(\Leftrightarrow 4x^2-4x-6x+6=0\)
\(\Leftrightarrow (x-1).4x-(x-1).6=0\)
\(\Leftrightarrow (x-1).(4x-6)=0\)
\(\Leftrightarrow \left[\begin{array}{} 4x-6=0\\ x-1=0 \end{array} \right.\)
\(\Leftrightarrow \left[\begin{array}{} 4x=6\\ x=0+1 \end{array} \right.\)
\(\Leftrightarrow\left[\begin{array}{} x=\dfrac{3}{2}\\ x=1 \end{array} \right.\)
Vậy S={\(\dfrac{3}{2};1\)}