Question

Answer 1

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

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

\(\Rightarrow\left|3x-1\right|=7\)

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

Answer 2

Ta có: \(\sqrt{9x^2-6x+1}=7\)

\(\Leftrightarrow\left|3x-1\right|=7\)

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