Đáp án:
Giải thích các bước giải:
Dấu " = " xảy ra khi ( x+2020 )( x + 2021 ) ≥ 0
⇔ \(\left[ \begin{array}{l}x + 2020 \geq 0 \\x + 2021 \geq 0\end{array} \right.\)
\(\left[ \begin{array}{l}x + 2020\leq 0\\x + 2021\leq 0\end{array} \right.\)
⇔ \(\left[ \begin{array}{l}x\geq - 2020\\x\geq - 2021\end{array} \right.\)
\(\left[ \begin{array}{l}x\leq -2020\\x\leq -2021\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x\geq -2020\\x\leq - 2021 \end{array} \right.\)
