Ta có `: | 2x + 4 | ≥ 0 ; | x + y + 2021 | ≥ 0`
`⇒ | 2x + 4 | + | x + y + 2021 | ≥ 0`
Mà `| 2x + 4 | + | x + y + 2021 | = 0`
`⇒` \(\left[ \begin{array}{l}2x + 4 = 0\\x + y + 2021 = 0\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}2x = - 4\\x + y = - 2021\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}x = - 2\\x + y = - 2021\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}x = - 2\\y = - 2019\end{array} \right.\)
Vậy `; x = - 2 , y = - 2019 .`
