2 câu trả lời
`\sqrt{x^2-6x+9}=2021` `(x∈R)`
⇔`\sqrt{(x-3)^2}=2021`
⇔`|x-3|=2021`
⇔\(\left[ \begin{array}{l}x-3=2021\\3-x=2021\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=2024(tm)\\x=-2018(tm)\end{array} \right.\)
Vậy `S={2024,-2018}`
Đáp án:
`sqrt{x^2-6x+9}=2021`
`<=> sqrt{(x-3)^2}=2021`
`<=> |x-3|=2021`
`<=>`\(\left[ \begin{array}{l}x-3=2021\\x-3=-2021\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x=2024\\x=-2018\end{array} \right.\)
Vậy `S={-2018;2024}`