Đáp án:
` S={1;-2020/2019}`
Giải thích các bước giải:
`2019x^2+x-2020=0`
`->2019x^2-2019x+2020x-2020=0`
`->2019x(x-1)+2020(x-1)=0`
`->(2019x+2020)(x-1)=0`
`->` \(\left[ \begin{array}{l}2019x+2020=0\\x-1=0 \end{array} \right.\)
`-> ` \(\left[ \begin{array}{l}x=\dfrac{-2020}{2019}\\x=1\end{array} \right.\)
