`sqrt{x^2-6x+9}=7x+1`
`<=>sqrt{(x-3)^2}=7x+1`
`<=>|x-3|=7x+1`
`ĐK:x>=-1/7`
`=>` \(\left[ \begin{array}{l}x-3=7x+1\\x-3=-7x-1\end{array} \right.\)
`=>` \(\left[ \begin{array}{l}6x=-4\\8x=2\end{array} \right.\)
`=>` \(\left[ \begin{array}{l}x=-\dfrac{2}{3}(loại)\\x=\dfrac{1}{4}(TM)\end{array} \right.\)
