Power series coefficients for f(x)=5x arctan(3x)

[rocksteady]

Homework Statement

The function $$f(x)=5xarctan(3x)$$ is represented as a power series. Find the first few coefficients in the power series.

Homework Equations

The power series is represented in the form $$sum(Cn*x^n)$$

The Attempt at a Solution

I've attempted to write the function as an integral, and split the 5x with the trignonometric component. After doing this (and writing a power series), I'm not getting the right answer. Is something wrong with my approach?

Thank you in advance.

 

[rock.freak667]

Take f(x)=tan$^{-1}$x and find the taylor series of it at $\alpha=0$ and the replace x by 3x and multiply by 5x after