Question

Giải các phương trình sau: √9x^2 - 6x + 1 = 7

Answer 1

\(\sqrt{9x^2-6x+1}=7\left(x\in R\right)\)

\(\Leftrightarrow\sqrt{\left(3x-1\right)^2}=7\)

\(\Leftrightarrow\left[{}\begin{matrix}3x-1=7\\3x-1=-7\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{8}{3}\\x=-2\end{matrix}\right.\)

Vậy : \(S=\left\{-2;\dfrac{8}{3}\right\}\)

Answer 2