`|x^2 - 4x + 5| - 5 = 3x`
`-> |x^2 - 4x + 5| = 3x + 5` `(D = [-5/(3); +infty))`
`->` \(\left[ \begin{array}{l}x^2 - 4x + 5 = 3x + 5\\x^2 - 4x + 5 = -3x - 5\end{array} \right.\)
`->` \(\left[ \begin{array}{l}x^2 - 7x = 0\\x^2 - x + 10 = 0 (vô\ nghiệm)\end{array} \right.\)
`->` \(\left[ \begin{array}{l}x = 7\\x = 0\end{array} \right.\) `(TM)`
`-> S = {0; 7}`