By recalling that e^ln(a) = a, you can rewrite 3^2x as e^2xln(3).

Then, you can differentiate this like any other e function, by using the product rule.

d/dx (e^2xln(3)) = e^2xln(3) x d/dx (2xln(3))

d/dx (e^2xln(3)) = e^2xln(3) x 2ln(3)