d/dx of taninverse e^3x

i know tan inverse is 1/1+x^2 but im not sure what to do with e^3x?

As usual, just use the chain rule:

Let u = e^3x, and you have

d/dx arctan(u) = 1/(1+u^2) * du/dx
= 1/(1+u^2) (3e^3x)
= 3e^3x/(1+e^6x)