Câu này làm gì có m hả em?
\(7x^2-9x+2=0\\ \Leftrightarrow7x^2-7x-2x+2=0\\ \Leftrightarrow7x\left(x-1\right)-2\left(x-1\right)=0\\ \Leftrightarrow\left(7x-2\right)\left(x-1\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}7x-2=0\\x-1=0\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=\frac{2}{7}\\x=1\end{matrix}\right.\\ \Rightarrow S=\left\{\frac{2}{7};1\right\}\)