Start with
[tex]4(6x-1)^2-5=223[/tex]
Add 5 to both sides:
[tex]4(6x-1)^2=228[/tex]
Divide both sides by 4:
[tex](6x-1)^2=57[/tex]
Which implies
[tex]6x-1=\pm\sqrt{57}[/tex]
Add 1 to both sides
[tex]6x=\pm\sqrt{57}+1[/tex]
Divide both sides by 6:
[tex]x=\dfrac{\pm\sqrt{57}+1}{6}[/tex]