[tex] \sqrt{ 9x^{2} -6x+1} + \sqrt{ 9x^{2} +6x+1} = \\= \sqrt{ (3x-1)^{2}} + \sqrt{ (3x+1)^{2}} = \\= |3x-1|+|3x+1| = \\= |3x-1|+|3x+1| \\ |x|\ \textless \ = \frac{1}{3} \\ \frac{-1}{3} \ \textless \ =x\ \textless \ =\frac{1}{3} \\ (3x+1)\ \textgreater \ =0 ..oricare..ar..fi..x \\ (3x-1)\ \textless \ =0..oricare..ar..fi..x \\ |3x-1|+|3x+1|= \\ =1-3x+3x+1=\\=2[/tex]
