I'm assuming you mean [tex](3x)^2 - 1[/tex], not [tex](3x)^{2-1}[/tex]. To evaluate this when [tex]x = 2[/tex], simply evaluate the expression when the number 2 takes the place of [tex]x[/tex].
Thus, we can find:
[tex](3 \cdot 2)^2 - 1[/tex]
[tex]6^2 - 1[/tex]
[tex]35[/tex]
Our answer is 35.
