√(x^2 -6x +9) = 2021

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}`