$$- \frac{10}{25 x^{2} + 1}$$
500*x
------------
2
/ 2\
\1 + 25*x /
$$\frac{500 x}{\left(25 x^{2} + 1\right)^{2}}$$
/ 2 \
| 100*x |
500*|1 - ---------|
| 2|
\ 1 + 25*x /
-------------------
2
/ 2\
\1 + 25*x /
$$\frac{- \frac{50000 x^{2}}{25 x^{2} + 1} + 500}{\left(25 x^{2} + 1\right)^{2}}$$