\(\left[{}\begin{matrix}x=\dfrac{7-\sqrt{17}}{8}\\x=\dfrac{7+\sqrt{17}}{8}\end{matrix}\right.\)
\(\Leftrightarrow\left(x-2\right)\left(4x+1\right)=0\)
\(\Leftrightarrow x-2=0\) hay \(4x+1=0\)
\(\Leftrightarrow x=2\) \(\Leftrightarrow\) \(4x=-1\)
\(\Leftrightarrow x=-\dfrac{1}{4}\)
Vậy \(S=\left\{2,-\dfrac{1}{4}\right\}\)
\(\Delta=\left(-7\right)^2-4\cdot4\cdot2=49-32=17\)
Do đó: Phương trình có hai nghiệm phân biệt là:
\(\left\{{}\begin{matrix}x_1=\dfrac{7-\sqrt{17}}{8}\\x_2=\dfrac{7+\sqrt{17}}{8}\end{matrix}\right.\)
