[tex](3x+9x)^{14}=67[/tex]
[tex](12x)^{14}=67[/tex]
take 14th root of both sides (like cube root but 14th)
remember to take positive and negaitve roots
[tex]12x=+/-\sqrt[14]{67}[/tex]
divide both sides by 12
[tex]x=\frac{+/-\sqrt[14]{67}}{12}[/tex]
[tex]x=\frac{sqrt[14]{67}}{12}[/tex] or [tex]x=\frac{-sqrt[14]{67}}{12}[/tex]