Question

(2021-x).(x+2021)=0

Answer 1

\(\left(2021-x\right)\left(x+2021\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=2021\\x=-2021\end{matrix}\right.\)

\(\Leftrightarrow x=\pm2021\)

Answer 2

\(\Rightarrow2021-x=0\) hoặc \(x+2021=0\)
\(\Rightarrow x=2021\) hoặc \(x=-2021\)
\(\Rightarrow x\in\left\{2021;-2021\right\}\)

 

Answer 3

giải chi tiết giúp mình nhé