See, pls, the suggested explanation:
3(5x-1)²=27 ⇔ 75x²-30x-24=0 ⇔ 25x²-10x-8=0 ⇒
[tex] \left[\begin{array}{ccc}x= \frac{5-15}{25} \\x= \frac{5+15}{25} \end{array}\right \ =\ \textgreater \ \ \left[\begin{array}{ccc}x=- \frac{2}{5} \\\ x= \frac{4}{5} \end{array}\right[/tex]
