1: \(\left\{{}\begin{matrix}2x+y=10\\5x-3y=3\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}6x+3y=30\\5x-3y=3\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}11x=33\\2x+y=10\end{matrix}\right.\Leftrightarrow}\left\{{}\begin{matrix}x=3\\y=4\end{matrix}\right.\)
2: \(3x^2-2x-1=0\)
\(\Leftrightarrow3x^2-3x+x-1=0\)
=>(x-1)(3x+1)=0
=>x=1 hoặc x=-1/3