2*x
----------
/ 4\
| x |
7*|1 + --|
\ 49/
$$\frac{2 x}{\frac{x^{4}}{7} + 7}$$
/ 4 \
| 4*x |
14*|1 - -------|
| 4|
\ 49 + x /
----------------
4
49 + x $$\frac{1}{x^{4} + 49} \left(- \frac{56 x^{4}}{x^{4} + 49} + 14\right)$$
/ 4 \
3 | 8*x |
56*x *|-5 + -------|
| 4|
\ 49 + x /
--------------------
2
/ 4\
\49 + x / $$\frac{56 x^{3}}{\left(x^{4} + 49\right)^{2}} \left(\frac{8 x^{4}}{x^{4} + 49} - 5\right)$$