Minor simplification problem in integral

[ijabbott]

I think it should have cancelled the outer 'a' with the inner denominators.

MathJax version for posterity:

\[ \int\frac{a}{{(a^2+x^2)}^2}dx \to a* \left(\frac{x}{2*a^2*(a^2+x^2)}+\frac{\mathsf{ATAN}(\frac{x}{a})}{2*a^3}\right) \]