`text{đkxđ ∀ x}`
`sqrt(9(2-3x)^2) - 6=0`
`<=> sqrt(9(2-3x)^2) = 6`
`<=> 9(2-3x)^2 = 36 text{bình phương hai vế}`
`<=> (2-3x)^2 = 4`
`<=> $\left[\begin{matrix} 2-3x=2\\ 2-3x=-2\end{matrix}\right.$ `
`=> $\left[\begin{matrix} x=0\\ x=4/3 \end{matrix}\right.$`